Dermatology for the Small Animal Practitioner (Made Easy Series)

Dermatology for the

S ma ll Anima l Pra ctitioner

Ral£ S. Mueller D r. rne d .ver., MACYSc, D ;pA

YO, FA CYSc

Made Easy Series Teton

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Dermatology fo r the Small Anima l P ractitio n e r by R a lf S . Mu e lle r, Dr. med.vet .• MACVSc, OipA C VO, FAC V Sc

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1-893441-06-7

Print numbe r 5 4 3 2 1

Library o f Congress

Ca tal og in g~ in ~ Publi cat i o n

Mueller, Ra lf S. Derma to logy fo r the smat! a nimal practitio n e r p. cm . ~~ (M ade easy series)

Data

I Ralf S. Muelle r.

ISBN 1-893441-06-7 (a lk. pape ,) 1. Veterinary dermatology. 2 . Dogs ~~Di seases ~~Trea tm e nt . 3. Cats~~Diseases ~~Treatmen.t. I.

Title . I I. Made easy series (J ackson, Wyo.)

S F992.S55 M83 2000 636.089'65--dc21 00-059976

Dedication T o m y wife , pa rm e r, and best friend, Son ya Bette n ay, whose continued love, su pport, a nd fe edback h as h elped

Il"le

tre m e nd o us ly over d1.e

yea rs pe rson a ll y a nd pro fess io n a ll y. With o ut h e r this book wo uLd not

have been poss ib le. T o m y pa re nts , Irmi a nd S ig i, w h o enco uraged a nd suppo rte d me w h e n I le ft Ge rtTla n y to le a rn Ill.o re ab o ll t ve te ri n a ry d e rm a t o l.ogy and wh o yea rs late r Looked after the c hildre n to g ive m e tim e to write this book . To m y c hildre n , An ya a nd Flo rian, w h o se inte res t a nd pe rs iste n ce in lea rning a re a con sta nt !5ource of arnaze nl e nt a nd inspi ra ti o n to m e. T o m y m.e nto rs, Pe te r Ihrke and T o n y S t a nn a rd , a nd to a ll th e c o lleagues w h ose s uppo rt a llowed me to d e velo p th e kn o w le d ge a nd ex pe ri e n ce th at I h o pe w ill m a ke this book usefu l in SIn a l! a nilna l prac ti ce . S pecific th anks to Drs. C aro l Fo il , Ga il Kunk le, Ke rr ie La y, H e le n Po we r, D av id R o bso n , a n d Linda Vogel n est, a nd th e ed ito ria l team w ith C indy R oan tree, S usan Hunsbe rge r, a n d R a y Luke n s fo r th e ir input a nd to D rs. Son ya Be ttena y, Peter Ih rke , Th ie rry O li vry, W a yn e R ose nkra ntz, and Michael S hi pst o n e fo r prov iding some o f the pi c t u res .

•

Preface Dear Colleagues, Veterinary derm:=ttology plays an itupo rra nt ro le in slna ll a ninl a i p ract ice. S kin proble lTIS a re the m ost freq u e nt presenting co mpla int

in m a n y practices but du e to th. e il' o fte n c hron ic nature m ay ca lise fru s tra tion for vete rin a ri a ns , clie nts, a nd patients a li ke.

Thi s book is a prac tica l. introd ucti o n to vete rin a ry dernl a to logy for th e busy s nla il a nim a l prac titio n e r. It w ill h e lp YO LI to di.ag n ose a nd tn a nage s kin diseases seen eve ry day in yo ur practice a n d a llo w you to pe rfo rm a so lid workup in pa tients with ra re o r comp licated s kin diseases that Ill.ay req uire further read ing, refe rra l to, o r advice from a veterinary denn ato logist.

M ost o f a ll , I h ope it wi ll a llow you to e njoy your dermatology cases, provide good se rvice, and improve the quality of life in your pa ti e nts. Beca use your opini o n s a nd co ncerns are impo rta nt in 111aking this boo k

ITIOS t

usefu l for th e s lTla ll anima l prac t iti o ner. I wou ld app rec i;

ate it if yo u wou ld m a i l o r e mail [TIe a n y c riti c ism s o r s ugges ti o n s fo r inclus io n in future ed itio n s. W a rm rega rds. R a lf S. Mueller, Dr. m ed.vet. , MACVSc, DipACVD, FACVSc Department o f C lin ical Sciences College o f Veter inary M edicine a nd Bio l11e clical Sc ie n ces Colo rado S tate Uni ve rs ity Fo r t Co llins, CO 80526, USA Emai l: nnueller@vth .co lostate.edu

•

Table of Contents Section

1

"How To"

Der mato log ic Hist ory

2

D e rmato lo gic E x amination

11

S pec if ic T e sts in Small A nim al De r mato logy

21 21 26 28 30 32 36

Cytology Superficia l S kin Scra p ings Dee p S ki n Scrap ings Wood's Lamp Exam ination Fung al C u lt u re Tricho gram Bio p sy Serum T e sting for A l lergen-spec if ic IgE Bacte r ia l C u ltu re P atch T e sting

D iagnost ic Trials E l im inat ion D iet I n se c t C ontrol Tria l. Scab ie s T reatm e nt T r ial.

Section

2

38 42 43 44

46 46 48 49

The Approach to Common Dermatologic Presentations

The Pruritic Dog

53

T he Dog with P a pule s, Pustules a nd C rusts

58

The Dog w ith A lopecia

69

The D o g w ith Nod u les

76

T h e Dog with Nasal D ermatitis

83

The Cat w ith M il iary D e rmatitis

87

The Cat with Nonin flammatory A lopecia

92

The C a t w ith Le si ons of t he E o sino p hilic Granuloma Comp lex

96

The C a t with N odule s

.

100

T he P atient with O t itis Ext e rna

Section

3

107

Treatments

S hampoo The ra p y of V arious Skin Condit ions

11 5

T reatment of Bacte r ia l Infe c tion . . . . . . . . ..

1 18

Treatment o f P ru r itus

123

A lle rgen-specific I m mun o the ra p y Antih istam ine s Esse ntia l Fa t t y A c ids .. _ G luc o c o rtic o id s

123 125 _ . . 12 8 12 9

T re a tment of F u nga l Infe c t io n s

130

Ectoparas itic id a l Agents

133

Inse c t Con t rol Tria ls and Individ ual M anagement o f P atients w it h Fle a -b ite Hype rse n sitiv it y

136

Immuno su p pre ssi v e T herapy. . . . . . . . . . . . .

141

Treatment o f A lo p e cia d u e to H orm o n a l D iseases and Fo ll ic u lar Dysplasia .

144

Appendices

145

A. Breed Pre dile c tions .

145

B. Q uest ion na ire. . .

149

Recommended Readings

15 1

General Principles The main goal of this book is to provide a readily useable reference for veterinary dennatology that allows the thorough and logical workup of a patient seen for skin disease. It also provides therapeutic protocols for the Inost

COln~

moll. dennatologic problern.s. There are three sections to this book. The first covers how to take a dennatologic history, interpret the results of this history in light of the clinical findings, and decide on and perfo nn necessary tests. The second explains the approach to certain conunon dermatologic problell.1.s in small ani11.l.al practice. The last SUll.1.rnarizes therapeutic options for specific conditions.

Some Helpful Hints Scattered throughout the text, you will find the foHowing symbols to help you focus all. what is really im.portanr: ./

This is a routine feature of the subject discussed.

h

We wiH use this selectively. This is a key point to understanding this particular topic.

~

Stop. This does [lot look inl.portant, but it can really Iuake a difference.

fj7:c. SOlnething serious will happen if you do not relnember thi.s, possibly resulting in the loss of both patient and client.

*

Drugs and Diseases luarked with an asterisk and a colored screen in the tables i.n Sections 2 and 3, are potentially difficult and/or are dangerous. You may consider referral to a veterinary specialist or seek further advise from a colleague with more know ledge about the drug or disease.

Section

1

"How To"

In this section, I discuss key questions important in taking a derLnatologic history and their implications, as well as specific derLnatologic lesions and what they tell us. F urthennore, I introduce various tests ilnportant in veterinary dermatology, give their indications, explain necessary techniques in'detail, and discuss the interpretation of the resu 1ts.

Dermatologic History Clinical signs for various skin diseases aTe very sin1.ilar and the etiology of a patient's problelnmay not be apparent based solely on the findings of a clinical eX3lTlination. A thorough history will typica lly provide clues in regard to the cause of the skin dis order and a ll ow the veterinarian to prioritize time-cons..... lming and frequently costly laboratory tests needed to confinn the diagnosis . I prefer lny clients to fill out a questionnaire in the waiting [OOIn which we then review t ogether during the consultation. This decreases the time needed to extract a good history from the owner, helps ensure a complete history independent of stress levels and tiine constraints, and allows the client to think about her or his pet's skin problem for a little while without unnecessarily delaying the appointment schedule. A salnple of a dennatology questionnaire is enclosed in the Appendix. It is ilnportant to phrase questions appropriately, because many owners leave out pertinent facts either because they are not aware of cheir relevance or b ecause they think these facts may not be well received by the veterinarian. Som.etimes, it is necessary to ask the same question several times in different ways to obtain lTleaningful answers. I cannot overemphasize the ilTlportance of taking a good and efficient d ermatologic history, which requires tremendous knowl e dge, experience, practice, and effective comLnunication skiLLs. To teach this is beyond the scope of this book. However, do d iscuss SOUl.e crucial questions and their implications in more d e tail.

Question: What is the breed of the patient? Relevance ../ SOlne breeds are predisposed to certain skin diseases and it lnay be worthwhile to keep a list of such breed predispositions in easy reach . ../ A list of reported breed predisposition is given in the Appendix. But beware, breed predispositions may vary with geographic location! 2

Question:

How old was the patient when clinical signs were

first recognized? Relevance

./ Very young anilTIals (puppies and kittens) are more COIUlTIOnly presented with congenital and hereditary defects, ectopara~ sites such as Sarcoptes scabiei, Otodectes cynotis, or Demodex canis, infections with bacteria (im_petigo) or fungi (denuatophytosis) or, in dogs, canine juvenile sterile granulo~ ITlatous dermatitis and lYluphadenitis . ./ Young adult dogs are rnore commonly affected by demodicosis, atopic denuatitis, and flea~bite hypersensitivity, as well as idiopathic seborrhea and follicular dysplasia . ./ In lTIiddle age, horn"lonal diseases becorne a significant consid~ eration, although allergies still occur in a significant nurnber of anintals, particularly in cats . ./ Neoplastic diseases are m.ore cOlnnlonly seen in older animals.

Question:

How long has the disease been present and how did it progress?

Relevance

./ Acute onset of severe pruritus is frequently associated with scabies. Food adverse reaction Iuay also have an explosive onset .

./ If pruritus was the first initial sign and lesions occurred later, then atopy or food-adverse reaction are most likely. Pruritus with lesions that occur at approxim.ately the same tilne may be due -to a wide variety of causes . ./' Chronic nonlesional pruritus is typically due to atopic der~ Inatitis or food adverse reaction, possibly complicated by sec~ ondary infections. Scabies incognito may also cause nonlesLonal pruritus .

./ If cutaneous signs have been present for years without the development of concurrent systeluic signs, endocrine disorders are unlikely . ./ Nonpruritic alopecia for years without systeluic signs points towards alopecia and follicular dysplasias or hereditary alopecia . ./ The presence of chronic wounds alone or associated with draining tracts necessitates the search for an infectious organism. 3

Diagnostic procedures: Scabies treatment trial, skin scrapings elilnination diet, cytology, bacterial culture, fungal culture, b iopsy.

Question:

Where on the body did the problem start?

Relevance Tables 1 ~ 1 and 1 ~2 outline typically affected sites of certain diseases.

4

Table 1-1 location of lesions and/or Pruritus of Various Canine Skin Diseases LOCATION OF LESIONS AND/OR PRURITUS

COMMON UNDERLYING DISEASES

Otitis externa

Atopy, food adverse reaction, parasites, polyps. Secondary infections are common and can also occur with primary endocrine disease!

Pinnae

Atopy, food adverse reaction, scabies, vasculitis, pemphigus foliaceu s

Head/face

Demodicosis, atopy, food adverse reaction, dermatophytosis, insect allergies, scabies, discoid lupus erythematosus, pemphigus foliaceus

Paws

Demodicosis, atopy, food adverse reaction,

Malillsezia dermatitis, pemphigus foliaceus, metabolic epidermal necrosis. Claws

Bacterial or fungal infection, trauma, immune-mediated skin diseases .

Tail base

Flea-bite hypersensitivity

Table 1-2 Location of lesions or Pruritus of Various Feline Skin Diseases lOCATiON OF LESIONS AND/OR PRURITUS

COMMON UNDERLYING DISEASES

Otitis externa

Atopy, food adverse reaction, parasites, polyps. Secondary infections common~

Pinnae

Notoedres wti, vasculitis, pemph igus foliaceus

Head/face

Atopy, food adverse reaction, dermatophytosis, insect allergies, feline scabies, pernphigus foliaceus

Paws

Atopy, food adverse reaction, pemphigus foliaceus, trauma, plasmacytic pododermatitis

Claws

Bacterial infection, trauma, immune~medi()ted skin diseases

Tail base

Flea-bire hypersensi ti vity

Question:

Is, the animal itchy?

Relevance

./ Pruritus is sometimes difficult to identify. Owners often do not consider licking, rubbing, or biting as clinical signs indica tive of pruritus (we all have h eard the story of the dog who is constantly licking its feet because lIit is a very clean dog ... "). Severa l 5

routine questions may be needed to identify pruritus in SOITle patients: Are they licking or chewing their paws? Are they rubbing their faces? Do they scoot on their rear ends? Are they scratching their anTlpits? ./ The presence of pruritus with skin lesions does not help ITluch in discovering t he etiology of the pruritus, given that ITlany skin diseases cause pruritlls. However, pruritus without lesions typically means either atopic de nnatitis or food adverse reaction (possibly with secondary infections) or in rare instances scabies incognito . ./ The perceived severity of pruritus Inay vary with the owner. Some owners deny the presence of pruritus despite the patient1s frantic scratching in the consultation room. Others insist on severe pruritus in a patient with no evidence of sdftrauma on clinical exaLnination. Good communication skills and judgement are essential to form a re81istic opinion for evaluation. If the petls scratching wakes the owner lip at night, the pruritus is severe irrespective of the presence of lesions . ./ If itch preceeds the occurrence of lesions, atopic dennatitis, food adverse reaction, and scabies incognito rnust again be considered. Diagnostic procedures: Trichograrll. in alopecic patients that are reporredly nonpruritic.

Question:

Is the disease seasonal?

Relevance

./ Insect bite hypersensitivities (caused most cOlnmonly by fleas, but mosquitoes or other insects can also be invo lved) frequently cause disease that worsens in summer. Whether clinical signs are absent or milder in the coLder season depends on specific environmental cond itions . ./ Atopic dermatitis may also be seasonal in certain climates. In many telTIperate climates it may OCCllr lTIOre noticeably in spring and summer if caused by tree and grass pollens or worsens in sum~ mer and autLllnn because of weed pollens. Warmer clitnates such as those found in tropical or subtropical regions usually have an extended pollen season. Hypersensitivities to house dust ITlites are often nonseasonal, but may be seasonally worse in winter in sotne areas and patients. 6

. / Seasonal noninflammatory alopecia and hyperpigmentation may be due to cyclic follicular dysplasia. Diagnostic procedures: Insect bite trial, intradermal skin testing, serUln testing for allergen-specific IgE, biopsy, keeping the animal inside to evaluate for mosquito-bite hypersensitivity.

Question: Are there other clinical signs such as sneezing, coughing,

or diarrhea? Relevance . / Sneezing, coughing, wheezing, and conjunctivitis may be seen concurrently with atopic dennatitis and caused by airborne allergies . ./ Diarrhea may be associated with food adverse reaction . ./ Polydipsia and polyuria are comlnon with iatrogenic and idiopathic hyperadrenocorticislTI . ./ Systeluic mycoses frequently present with concurrent anorexia, Lethargy, and with gastrointestinal or respiratory symptoms. Diagnostic procedures: Cytology of nasal exudate or conjunctiva, eliluination d iet, urine cortisol/creatinine ratio, low dose dexamethasone suppression test, and adrenocorticotropic hormone (ACTH)stin"luLation test.

Question:

What is fed to the animal? Was a special diet used in the past? What was it and how long was it fed exclusively?

Relevance ./ Knowing the diet will allow the clinician to determine possib le nutritional deficiencies .

./ It will also help in formulating an eliLnination diet if indicated (p. 46), ./ If a diet was fed in the past and it was not a true elilnination diet (was not fed exclusively or not fed for an appropriate length of tirne) it may need to be repeated.

h

Contrary to the cominon b elief, food adverse reactions typically do not occur immediately after a change in feeding habits. Most animals with food adverse reactions have been consuming the offending diet for years before showing clinical signs.

~ Remember to ask about treats and supplements, which are

often forgotten, when food is discussed with the client.

Question: Are there other animals in the household? Do they show

cutaneous symptoms? Relevance ./' If other animals in the household are sirnilarly affected, contagious disease such as dennatophytosis or scabies is lnore likely. ~ Other anilnals may serve as a reservoir for ectoparasi tes

without showing clinical signs. Diagnostic procedures: If indicated, insect control tria l , fungal cultures, or scabies treatment trials should include all anilnals in the household to identify and/or treat possib le carrier anitnals to allow successful long-tenn remission for the patient.

Question:

Does any person in the household have skin disease?

Relevance ./' Two zoonoses of Inajor concern in veterinary dermatology are scabies and dennatophytosis (ringworm.). However, even if owners are not affected, these diseases cannot be ruled out . ./' Canine scabies affecting humans occurs as an itchy papular rash in contact areas, such as arms and legs, starting days to weeks after onset of pruritlls in the pet. ./' Dermatophytosis is often characterized by scaling and erythema and nlay not be p articularly pruritic, but occasionally can present as severely inflammatory and pruritic skin disease. Dennatophytosis lnay sometimes be Inisdiagnosed as eczema in humans . ./' Sporotrichosis and other mycoses have zoonotic potential and may occasionally cause disease in hUlnans . ./' Don't forget t hat the skin disease of the owner l1.1.ay also be com-pletely u nrelated to the a11.ilnal's skin disease. Diagnostic procedures: Wood's light, skin scrapings, fungal culture, scabies trial treatlnent . In severe f onns of suspected dermatophytosis, a biopsy and special funga l stains may prove useful for obtaining a quick diagnosis.

Question:

Was the disease treated before? If so, which drugs were used and how successful was treatment?

Relevance Response to previous therapy can be of tremendous help in establishing or ruling out underlying causes for the skin disease.

. / Initial response to recent glucocorticoid adtuinistration luay not be help ful because many skin diseases improve for a short period with th is syrnptomatic, nonspecific treatment . . / Repeated response to low~dose glucocorticoid therapy sug; gests hypersensitivities (possibly complicated by Malassezia dennatitis caused by Malassezia pachydermatis) . . / Repeated response to antibiotics and glucocorticoids in cOlnbination is of l ittle h elp . . / Repeated partial or tota l response to antibiotics indicates a pyodenua usually second ary to either atopic dermatitis, food adverse reaction, hormonal disease, or another less comrnon disorder that is suppressing t he skin's immune system. In addition to antibacterial treatluent, the underlying problem needs to be identified and treated to prevent recurrences. ~ Ask specifically how much the, pet improved while receiving

rn_edication because luany owners tend to judge a treatluent as not helpful if it did not cure the disease.

Question: What is currently used to control fleas? Relevance . / Flea~bite hypersensitivity is the most common hypersensi~ tivity and an extreluely COlUluo n skin disease in rnost small anilnal prac t ices. If flea~bite hypersensitivity is suspected, a flea control tria l should be cOlnmenced . . / Deta ils of the flea control for all aniluals in the household are imp ortant because in a severely allergic anitual, clinical signs can b e caused by a very small nLLlnb er of flea bites. Inconsi~ stent or ineffective flea control can be discovered only through detailed questioning. ~ Many owners take questions about their flea contr ol as an

insult to their own cleanliness and h ygiene. Good COlUlnunica~ tion s k ills are a great help. I own a f1ea~allergic dog and rou; tinely mention he r as an example, which breaks the ice and increases the client's willingness to listen and follow my instructions.

Question: When was rhe last medication given? Relevance . / Recent administration of tnedication may affect the clinical presen ta tion.

9

. / It Inay also affect various i nd icated diagnostic tests that Inay n eed to be postponed . ./ Long~tenn glucocorticoid therapy will affect the results of allergy t ests - both intradennal skin testing and serum testing for allergen~specific IgE. It will also affect histopathologic findings and the results of Inany blood tests . ./ Antihistamines and short~tenn systelnic and topical glucocor~ ticoids (i.e., < 4 weeks) may influence intradermal skin testing . ./ Sorne antibiotics, sLlch as trimethopriln~sulfonalnide cOLnbina~ tions, will affect blood concentrations of thyroxin. Others such as cephalosporins n"lay affect the glucose readings of some urine test strips . ./ Reluember to ask specific questions regarding heartworm pre~ vention, vitmuin supplements, or dewonning which are also fonns of phannacotherapy.

Question:

Does the animal get better with a change of environment (a weekend away or a day at the in-laws for example)?

Relevance ./ The anilual's improvement in another environment indicates involvement of an environmental allergen (airborne or contact) or irritant . ./ Lack of ilTIprovement does not rule out these allergies, in that airbonie and contact allergens lllay be the same in different locations (house dust Illites are found ahnost anywhere in the world).

10

Dermatologic Examination A good dermatologtc examination requires adeq uate lighting, a systematic and thorough approach, and should a lw ays include a genera l physical exam.ination. Observation from a distance shou ld be followed by close inspection of skin and mucous membranes. I start at the head, look at the lips, mouth, ears, run my hands through the coat of the trunk, lift up the tail to inspect the periana l area, and then examine the legs and feet with pads and claws. Next, the patient is rolled on his back - reluctant small pets are made to sit up in the lap of the owner; with larger dogs the front paws are lifted up for a short moment, which gives me the opportunity to exaluine the anin"lal's ventral aspects from the axillae to the groin.

General Observation LocaJized or Generalized Problem ./' Localized problems may be due to infectious organisms that gained entry at a certain site and spread only locally such as atypical mycobacterial or fungal infections . ./' Neoplastic disease is commonly localized, at least initi a lly. ./' Generalized disorders are more commonly due to hypersensitivities or systemic conditions such as endocrine disorders and immune-mediated or metabolic skin diseases. Symmetry ./' Bilaterally symmetric lesions are ty pically caused by internal disease such as hypothyroidism, hyperadrenocorticism, or pemphigus foliaceus . A llergies may a lso present with bilaterally symmetric syrnptoms . ./' Asymmetric lesions more common ly have external causes such as ectoparasites (e.g., demodicosis) or fungi (e.g., dermatophytosis).

Haircoat Quality, Color, and Shine ./' Is the haircoat dull or shiny? A dull haircoat may be due to metabo lic or hormonal diseases, nutritional deficiencies, or chronic skin disease . ./' Are there color abnormalities or changes and if so, did they occ ur

11

before or concurrent with t h e onset of skin disease or as a consequence of the disease. Hair color changes may be associated with hormonal disease or follicular dysplasia . ./ Changes in t h e hair quality (either to a coarse coat or to a fine puppy coat) may again p o in t to hormonal disease or follicular dysplasia. Close inspection of t h e skin and mucous membranes follows the general observation. Pay special attention to any ind iv id ual lesions. Primary lesions are initial eruptions tha t are caused directly by the underlying disease process. Secondary lesions evo lve from primary le s io n s 01- are caused by the patient (selftrauma) or e nvironment (medications). It is important that the clinician be able both to differentiate between primary and secondary lesions and to understand the underlying pathornec.han ism because this helps in the formulation of a relevant list of differential diagnoses. I next discuss the individual lesions and their implications and give the most common differential diagnoses for each lesion.

Primary Lesions Macule ". : ::

.~:Pt~~~t~~~. :~::~\~~:;;~ ~ ',;::

12

Figurel-1A Macule

Figure l -1B Macule

Definition: A focal, circumscribed, nonpalpable change in color 12 months

~

57

The Dog vvith Papules, Pustules, and Crusts Key Questions

./ What is the breed of this patient? (p. 2) ./ How old was this patient when clinical signs were first recognized? (p. 3) ./ How long has the disease been present and how did it progress? (p. 3) ./ On which part of the body did the problem start? (p. 4) ./ Is the animal itchy? (p. 5) ./ Is the disease seasonal? (p. 6) ./ Are there other clinical signs, such as sneezing, coughing, or diarrhea? (p. 7) ./ What do you feed the animal? Was a special diet used in the past? (p. 7) ./ Are there any ocher animals in the household? (p. 8) ./ Does anybody in the h.ousehold have skin disease? (p. 8) ./ Was the disease treated before? If so, which drugs were used and how successful was treatment 7 (p. 8) ./ What is used for flea control currentl y 7 (p. 9) ./ When was the last medication given? (p. 9)

Differential Diagnoses Papules may develop into pustules and crusts, and any dog with an acute papular rash may eventually show pustules or crusts. Some dise ases are characterized by papules that do not typically develop further into pustules (such as flea-bite hypersensitivity); other diseases typically show crusting as their predominant symptom (such as zincresponsive dermatitis). Tables 2-2, 2-3, and 2-4 list the major differential diagnoses for dogs with papules, pustules, and crusts. Lesions may be follicular or nonfollicular (Figure 2-10). Follicular papules and pustules indicate a pathologic process concentrating on the hair follicle, most commonly bacterial folliculitis, demodicosis , or derrnato58

phy tosis. N onfollicular le si ons m ay indic a t e pathologic p rocesses conce n t rat ing o n. t he e p iderm is, d ermis, o r d erma -epid ermal junction. s uch as superf ic ia l spreading pyoderma , flea-bite, co n tact hypersensit iv ity, O r Immune -mediared ski n diseases. Be a ware that some n o rifollicula r proces ses m ay o c c as io nally inv olv e h air follicles as well.

Nonfollicular papule and pustule

Follicular papule and pustule

...• ./

.

'---' . ~/

Figu re 2- 10

59

m

a

Table 2-2 Differential Diagnoses, Commonly Affected Sites, Recommended Diagnostic Tests, Treatment Options, and Prognosis in a Dog with Papules DISEASE

COMMONLY AFFECTED SITES

DIAGNOSTIC TESTS

TREATMENT

PROGNOSIS

Flea-bite h ypersensitivity (antigens in flea saliva injected during th e fleabite cau se an allergic reaction in sensitized dogs)

Dor sal lumbosacral area , caudomedial thighs, inguinal area, ventrum, and periumbilical are a (Figure s 2-11 and 2-12)

Flea control trial (p. 48) is best, serum or skin testin g for allergen -specific IgE (only diagnostic in presence of type I hypersensitivity, dogs with delayed hvpersensitivity to flea anti gens proVIde negative results to serum tests, p. 42.)

Flea con tro l (p. 136), antipruritic therapy (p . 123)

Fair to excellent de pending on climate and owner commitmenr

Bacterial infection (rvpically by Staphylococcus intennedius and typically secondary to an underlving disease)

Erythema , scaling, sebo rrh ea, alopec ia, papules, pustules, and crusts , either focal or generalized depending on underl ying disease (Figures 2-13 and 2-14)

Cytology (p. 21) , biopsy (p.38)

Antibacterial treatment (p . 118) ,shampoo therapy (p .lIs)

Good , if underlyin g d isease can be idenri fied and treated appropriately. Relapse like ly, if this is not possible

Demodico sis (probably a hereditary specific Tccll defect that permits abnormal proliferation of Demodex canis, a normal commensal mite of canine skin. This proliferation leads to a furthe r parasiteinduced imrnunosuppression. Adult-onset dernodicosis frequently secondary to hormonal diseases, neoplasia, steroids , or other chem otherapy. )

Localized form: Focal erytherna, alopecia and scaling, most commonly on the lace « 4 Sites). Generalized form: Erythema, alopecia, papules, plaques, pustules and crusts where large areas, more th an 5 areas, or paws are involved (Figures 2- IS, 2- I 6, and 2-17)

Deep skin scrapings (p. 28), hair plucks (p . 36), biopsy (p .38)

Localized form : 95% resolv e spontaneously, thus benign neglect or antimicrobial treatment on ly (p . 119). Genera lized form: Amitraz, ivermecrin, milbemycin (p. 133) , antibacterial treatment for secondary infection (p . 118)

Fair

Scabies (a highl y comagious disease caused by Sarcoptes scabiei vaT. canis)

Pinnae, elbo ws, ven trurn, and hocks

Superfic ial skin scrapings (p. 26) , Sarcoptes treat ment erial (p. 49 )

Antiparasitic agent s (p . 133) Exce llent

Dermatophytosis (de rrnat ophyres are transmitred by contac t with fun gal elemen ts )

Face, pinnae, paws (Figure 2- 18)

Wood's lamp (p. 30 ), rrichograiu (p. .36 ), fungal cuiMe (p, 32), biopsy (p. 38)

Antimycot ic agen ts such as G ood griseofulvin o r ketoconazoie (p . 131) . Top ical antifungal shampoos may decrease con tam ination of en viro nmerit (p . 115 ),

C ontact hvpersensitiviry (delayed hypersensitivity reaction to environm ental allergens, c1 in ically overlappi.ng with cont act irritan t dermatitis)

Ery thema, macu les, papules and/o r vesicles in hairle ss or sparse ly haired areas (scrotum, chi n, perine um , pa lmar/pla nta r in terdigital skin , ven tral abdomen) (Figure 2-19)

Wood's lam p (p, 30) , trichogram (p, 36), fungal culrure (p 32) , biopsy (p. 38 ), patch resting (p. 44)

Avoidance , whole-body suits, pen roxyphvlline at 15 mg/kg twice daily, glucocorticoids (p. 129 ).

Excellen t with identificati on and avo idance of allergen, fair with medi cal manage ment

Mast cell tumor"

Most commonly on the caudal ha lf of the body (Figure 2-20)

C ytology (p. 21), biopsy (p. 38)

Surgical exc ision, sterile water injecti on , glucocorticoids (p. 129) , chemoth erapy, radiation,

Gu arded

---;

A

Figure 2-11 A lopecia, lichenifica t io n , focal ulcera tion , a n d c ru sting o f the rail base in a n Ll- yea ro ld, sp ay ed La bra d o r Retrie ver m ixed breed with flea-b ite h ype rse n sit iv ity. O'l

Figu re 2-12 Alopec ia and lich en ification o n the ta il base of a I -ve ar-ol d , male Lh asa Apso cross with flea-bite h ypersensit ivit y.

Figure 2-13 Papules, plaques. and epidermal collarettes in a 6-year-old. castrated Border Collie with pyoderma.

Figure 2-14 Crusted papules in a 3-year-old, male castrated Labrador Retriever with bacterial pyoderma.

Figure 2-15

Figure 2-16

Papules, plaques, and crusts in a 4-year-old female Boxer with generalized demodicosis.

Severe pododerm.atitis in a l-year-old, castrated Rottweiler with generalized demodicosis.

Figure 2-18 Figure 2-17 Abdominal papules in a 4-year-old, spayed Terrier mixed breed with generalized demodicosis.

Severe crusting on the head of a lO-year-old, castrated Beagle mixed breed with dermarophytos is caused by Tricho/lhyton mentagTophyces. Note the sharp demarcation between affected and nonaffected skin frequently seen with TrichophytOn infections.

Figure 2-19 Papules and plaques resulting from contact hypersensitivity in a 3-year- o ld male Weimaraner. (Courtesy of Dr. Son ya Bettenay.)

Figure 2-20 Mast-cell tumor in a 5-year-old, castrated Labrador Retriever.

Figure 2-21

Figure 2-22

Papules, pustules, and crusting in a 6-yearold, castrated Labrador with severe pemphigus foliaceus.

Footpad hyperkeratosis in a 13-year-old, spayed Australian Carrledog with pemphigus foliaceus.

Table 2-3 Differential Diagnoses, Commonly Affected Sites, Recommended Diagnostic Tests, Treatment Options, and Prognosis in a Dog with Pustules DISEASE

Flea-bite hvpersensitivirv (antigens in flea saliva injected during the fleabite cause an allergic rcaction in sensitized dogs)

COMMONLY AFFECTED SITES

DIAGNOSTIC TESTS

TREATMENT

PROGNOSIS

Dorsal lumbosacral area, caudomedial thighs, inguinal area, ventrurn, and periumbilical area (Figures 2-11 and 2-12)

Flea control trial (p. 48) is best, serum or skin resting for allergen-specific IgE (only diagnostic in.presence of type I hypersensitivity, dogs with delayed hvperscnsirivirv to flea antigens provide negative results to serum tests (p. 123)

Flea control (p. 136), antipruritic therapy (p. 123)

Bacterial infection (rvpically by Staphylococcus intermedius and rypically secondary ro an underlving disease)

Erythema, scaling, seborrhea, alopecia, papules, pustules, and crusts, either focal or generalized depending on underlying disease (Figures 2-13,2-14, and 2-15)

C ytology (p, 2!), biopsy (p.38)

Antibacterial treatment (p. 118), shampoo therapy (p.115)

Good, if underlying disease can be identified and treated appropriate ly. Relapse likely, if th is is not possible

Demodicosis (probably a hereditary specific Tccll defect that pennits abnormal proliferation of Demodex canis, a norma! commensal mite of canine skin. This proliferation

Localized form: Focal ervtherna, alopecia and scaling, most commonly on the face « 4 sites). Generalized form: Erythema, alopecia, papules,

Deep skin scrapings (p. 28) , hair plucks (p. 36), biopsy (p.38)

Localized form: 95% resolve spontaneously, thus benign neglect or antimicrobial treatment only, p. 131).

Fair

Fair to excellent depending on climate and owner commitmerit

leads to a turtn er parasiteinduced irnrnunosuppression. Adult-onset dernodicosis frequently secondary to hormona l diseases, neoplasia, steroids, or other chemotherapy.)

pu stuies anu where large areas, more than 5 areas, or paws are involved (Figures 2-15, 2-16, and 2-17) pl (lque~ ,

Lienernllzed torrn: Arrurraz, iverrnectin , milbemyci.n. (p. 133) , ant ibacterial treatrnen t for secondary infection (p. 118)

,- r u~L')

Pemphigus foliaceus* Planum nasale, periocular (immune-mediated skin area, lips, dorsal muzzle, inner disease characterized by surface of pinnae, foot pads, imraepiderrnal pustule for- claw folds, nipples (in cats) marion due to pemph igus (Figure 2-21, 2-22, 2-23,2-43) anti bodies against an tigens in the intercellular connections. May be idioparhic drug-induced or paraneoplasric)

Cyto logy (p, 21) , biopsy (p.38)

Figure 2-24

Lar ge pu stu les in a 2-year-old, ca strated C how C h ow with pemphigus foli aceus (Courtesy of Dr. Thierry O livry) .

Foot-pad h yperkeratosis and crusting in a 9-yearold , spayed Germa n Shepherd with me tabolic ep ide rm al n ecrosis (Courtesy of Dr. Michael S h tpsto n e).

Figu re 2-2 5

V1

Fair with appropriate treatment, poor for cure (except drug-triggered pe mph igus)

Fig ure 2-23

Pe r ioc u la r e rythema , a lo pec ia, and crustin g in a 4- year-old , femal e Husk y with zincre sponsi ve dermatosis (Courtesy of Dr. Sonya Bettenay). O'l

Immunosuppression (p . 141)

Table 2-4 Differential Diagnoses, Commonly Affected Sites, Recommended Diagnostic Tests, Treatment Options, and Prognosis in a Dog with Crusts DISEASE

COMMONLY AFFECTED SITES

DIAGNOSTIC TESTS

TREATMENT

PROGNOSIS

Bacterial infection Flea-bite hypersensitivity (antigens in flea saliva injected during me flea hite cause an allergic reaction iJI sensitized dogs)

Dorsal lumbosacral area, caudomedial thighs, inguinal area, venrrurn, periumbilical area (see Figures 2-11 and 2-12.)

Insect control trial (p. 48), serum or skin testing for allergen-specific IgE (only diagnostic in presence of rvpe I hypersensitivity, dogs with delayed hvpersensitivity to flea antigens are negarive on serum rests, p. 42)

Flea control (p. 136), antipruritic therapy (p. 123)

Fair to excellent depending on climate and owner commitment

Demodicosis (probably a hereditary specific Tcell defect that permits abnermal proliferation of Demodex canis, a normal commensal mite of canine skin. This proliferation leads to a further parasiteinduced irnmunosuppressian. Adult-onset demodicosis frequently secondary to hormonal diseases, neoplasia, steroids, or other chemotherapy. )

Localizedform: Focal crytherna, alopecia and scaling, most commonly on me face « 4 sites). Generalized form: Ervrhema, alopecia, papules, plaques, pustules and crusts where large areas, more than 5 areas, or paws are involved (Figures 2-15, 2-16, and 2-17)

Deep skin scrapings (p. 28 ), hair plucks (p. 36), biopsy (p.38)

Localized form: 95% resolve spontaneously, thus benign neglect or antimicrobial treatment only, p. 131). Generalized form: Arnirraz, iverrnecrin, milbemycin (p. 133), antibacterial treatment for secondary infection (p. 118)

Fair

Scabies (a highlv contagious disease caused by

Pinnae, elbows, venrrurn, and hocks

Superficial skin scrapings (p. 26), Sarcoptes treatment trial(p.49)

Antiparasitic agents (p.133)

Excellent

C ytology (p, 2 L), biopsy (p. 38)

Immunosuppression (p, 141)

Fair with appropr iate treatme nt, poor for cure (except drug-tri ggered pemphigus)

Sarcoptes scabiei var. canis) Pemphigus foliaceus* Planum n asale, periocular (immune-mediated skin area , lips, dorsal muzzle , inner disease characterized by surface of pinn ae, foot pads, intraepidermal pustule cla w folds, n ipples (in cats) formation due to pemphi- (Figure 2-2 1, 2-22, 2-23, 2-43 ) gus ant ibodies against antigens in th e Inrercellular connect ions, May be idiopath ic drug-induced e r paraneoplastic ) ,-

en

"-J

Metaboli c ep ide rmal necrosis* (pa th ogenesis unclear)

Muzzle, mucocutaneou s junet ions, distal limbs, foot pads, elbows, hocks, ventrum (Figure 2-24)

Biopsy (p. 38)

Antimi crobial treatment, vita min an d mineral supplement, h igh-quali ty prot ein, intravenous am ino ac ids

Derm a toph ytosis (de rrnaroph yres are tran srni tted by co nt ac t with funga l elements)

Face, pinnae, paws (Figure 2-18)

Wood's lamp (p, 30), trichogram (p. 36). fungal culture (p, 32 ), biopsy (p. 38)

A ntimyco tic agents such as G ood griseo fulvin or kerocon azole (p , 13 1) . Topical ant ifungal sha mpoos may decrease contaminati on of env ironmen t.

Zinc-responsive dermatitis (Zinc deficien cy due to insufficient zinc in the d iet or insufficient absorption of zinc, especially in arctic breeds)

Pe riocular, perioral , pinnae, ch in, foot pads, planum nasale, pressure poi nts (Figure 2-25)

Biopsy (p. 38 )

Zinc supp lem ent at ion, lowdose glucocorrico ids [0 incr ease zinc absorption

Fair

Idiopath ic seborrhea* (primary kerat in ization defect as autosomal recessive trait with decreased epidermal cell renewal time and thu s hyperproliferation of epidermis, sebaceous glands, and follicular infundibulum. Second ary to inflammation, endocrine disease, or nutritional deficiencies)

Otitis extern a, digital hyperkeratosis, dry flaky skin , or seborr heic dermati tis predominantly on face, feet, ventral neck , and ventral abdo men (Figure 2-26)

Biopsy (p. 38 )

Antiseborrh eic shampoos (p, 115 ), moisturizers, retinoids, co rticoste roids (p . 129 )

G ood to guard ed for well-bei ng, poor for cure.

Dermato myositis (autosomal dominant in Collies and Shelties, first signs in puppies)

Erythema, sca ling alopecia, mild crusting in face (particulad y periocular area) eartips, carpal and tarsal regions, digits, tail tip, myositis, and in severe cases, rn egasoph agus

Skin biopsy, muscle biopsy, EMG

Vitamin E (200-800 iu/day), pentoxyphylline (20 mg/kg q 12 h ), fo r acute flares predn isolon e ( 1-2 mg/kg q 2.4 h )

Varies Dogs typicall y will not de teriorate furt her after 1 year of age.

Poor

Figure 2-26 Crusted papules and plaques ca used by idio path ic seborrhea in an 8-year-old, male castrated Cocker Spaniel.

Figure 2-27 The Dog with Papules, Pustules, or Crusts Cytology (p.21) Skin Scrapings (p.26)

Cytology Skin scrapings . 123 ), antih istamines (I'" 125 ), essential fatty acids (I". 128 ), glucocortic oids (p . 129)

Good for well-bei ng of the patient with co nt inued managemen r, guarded for cure.

Food adverse reacti on (mayor ma y not be allergic, commonly reaction to a protein , rarelv an addi tive , clinicall y indistinguishable from atopy)

Cranial half of th e body, venrral abdomen or gen era lized di sease

Trichogram (I". 36), elirnination diet (I". 46)

Av oidance , antihistamines (I'" 125) , essential fatt y acids (I'" 128) , glucocorticoids (I". 129)

Excellent. if offending proteints) is (are) identified and avo ided. Fair with co n t inued management, if offending proteins are not identified. Guarded fo r cure.

Dermamph yto sis (in this form t ypically caused by M. canis)

Focal or generalized

Tuchograrn (I'" 36), cyt ology (p . 21), Wood's lamp (p, 30) , h.lI1gal culture (p, 32), biopsy (p . 38)

A ntifungal agen ts (I'" 13 1)

Poor for catte ries and Pe rsians , good o t herwise.

Psych ogenic alop ecia (due to exce ssive grooming caused by psvchol ogical factor s)

Medi al forel egs, caudal abdomen, inguinal region.

Hist ory (p. 2), rrichogram (p.36)

Environmental changes, glucocorticoids (p . 129) , anxi olvtic drugs.

Fair

(hyp ersensitivitv to aeroallergens such as pollens, .house dust mites, or mold .spores)

\D W

COMMONLY AFFECTED SITES

Flea- bite h ypersensiti vity

Table 2-9 continued DISEASE

COMMONLY AFFECTED SITES

DIAGNOSTIC TESTS

TREATMENT

PROGNOSIS

Hvperadrenoccrticism" (very rare, similar pathogenesis to same condition in dogs)

Polydipsia, polyuria, weight loss, anore-xia, polyphagia, depression , muscle wastin g, alopecia (flanks, ventrum, or entire m ink ), fragile skin

Ultrasonography, ACTH stimulation test, low-dose dexame thasone suppressia n test

Metyrapone, o,p'-DDD, ketoconaaole have been used

Poor

Anagen defluxion (severe diseases or an tim itotic drugs interfere with hair growth, resulting in abnormal ha ir shafts, which causes hair to break off suddenly)

Alopecia of sudden onset

History, rrichogram (p. 36)

Addressing the underlying cause

Excellent if causative factor is removed

History, trichogram (p. 36)

Not needed, if stress was a singular event

Excellenc

Focal to gene ralized alopecia Telogen effluvium (severe stress, such as shock , fever, surgery causes abrupt cessation of hair growth and switch ing to caragen and then telogcn phases in many follicles, which are all shed simultancously 1 to 3 months afrer rhe insult)

Figure 2-51 Noninflammatory alopecia in a cat with atopy. (Courtesy of Dr. Wayne Rosenkrantz.)

Figure 2-52 The Cat with Noninflammatory Alopecia

Trichogram (p.36)

Brok en off hair shafts

Remission

Fungal spores

Tapered hair shafts

No response

I ~ination diet (p~ I

No response

Remission

No relapse

Relapse

I Monitoring I

Relapse lateran

95

The Cat vvith Lesions of the Eosinophilic Granuloma Complex Key Ques tions v' How old was this patient when clinical signs were first recognized? (p.3) v'Is the disease seasonal? (p. 6) v' Are there other clinical signs such as sneezing, coughing, or diarrhea? (p. 7) v' What do you feed the animal? Was a special diet used in the past? (p. 7) v' Was the disease treated before? If so, which drugs were used and how successful was treatment? (p. 8) v' What is used for flea control now? (p. 9) v' When was the last medication given? (p. 9)

Differential Diagnoses All subsets of the eosinophilic granuloma are mucocutaneous reaction patterns in the cat. v'Indolent (or eosinophilic or rodent) ulcer commonly affects the upper lip unilaterally or bilaterally (Flgure 2-53), but may occur in the oral cavity or elsewhere on the body (Figure 2-54). The well-circumscribed ulcers with raised borders are rarely painful or pruritic; frequently the owner is more bothered by the lesions than the cat. The differential diagnoses of the feline eosinophilic ulcer are neoplastic diseases such as squamous cell carcinoma and infectious ulcers (eosinophilic ulcers are often secondarily infected as well). Diagnosis is confirmed by biopsy (p.38). Prior antimicrobial treatment (p. 118) is recommended if cytology (p. 21) is indicative of infection.

96

./ Eosinophilic plaques occur typically on the abdomen or medial thighs. are well-circumscribed. and severely pruritic (Figure 2-55) . ./ Eosinophilic (linear) granu lomas are nonpruritic. raised. firm. yellowish. and clearly linear plaques and occur most common ly on the caudal thighs (Figure 2-56). Differential diagnoses of both eosinophilic plaques and g ranulomas include neoplasias and bacteri a l and fungal granulomas (Tab le 2-10). Diagnostic procedures of choice a re cyto logy (p . 21) and biopsy (p. 38). After the diagnosis has been confirmed, the unde rly ing cause need s to be identified, if possible. and treated.

Figure 2-53 Indolent ulc er in a 2-y ea r-old female DSH.

Figure 2-54 Indolent ulcer of th e njpple in a 4-yearold fema le DSH.

Figure 2-55 Eosinophilic plaque~ in the inguinal area of a DSH. (Courtesy of Dr. Sonya Bettenay.)

97

Figure 2-56 linear granuloma in a male 8-year-old

DSH.

Table 2-10 Underlying Causes and Recommended Diagnostic Tests in a Cat with Lesions of the Eosinophilic Granuloma Complex Flea-bite hypersensitivity

Flea control trial (p.136)

Flea control (p. 136), glucocorticoids ( p. 129 ) , an tihistamines (p, 125), essential fatty acids(p. 128)

Atopy (hypersensinvicv to aeroalle rgens such as pollens, house dust mites, or mold spores)

Diagnosis based on hisrorv, physica l ex amination and ruling Out differen tial diagnoses. Intraderma l sk in test a llows formulation of

Allergen-speci fic immunotherapy (p . 123), antihistamines (p. 125), essential fatty acids (p.l28), glucocorticoids (p. 129)

immunotherapv.

98

Elimination diet Food adverse reaction (mayor may not be aller- (p.46) gic, commonly reaction to a protein, rarely an addirive, cl inically indistinguishable from atopy)

Avoidance, antilustarnines (p, 125), essential fatty acids (p. 128), glucocorticoids (p. 129 )

Idiopathic eosinophilic granuloma (most lik e ly gen er ic basis)

Glucocorricoids (p. 129), antibiotics (p. 119 )

Ruling out possible hypersensiriviti es

Figure 2-57 The Cat with Lesions of the Eosinophilic Granuloma Complex

Insect control (p. 48) with or without antimicrobial treatment (p .118) , ..

Remission

No improvement

No change

Remission

No relapse l ,)"", Lt:::~L"'Sl

r---

~

Relapse later on

Relapse

I

Monitoring

99

The Cat vvith Nodules Key Questions

./ How old was this patient when clinical signs were first recognized? (p.3) ./ How long has the disease been present and how did it progress? (p. 3) ./ Are there o cher clinical signs such as sneezing, coughing, or diarrhea? (p. 7) ./ Was the disease treated before? If so, which drugs were used and how successful was treatment? (p. 8)

Differential Diagnoses Th e differential diagnoses depend primarily on two features: the number of lesions and whether draining tracts are present or not. Is there only one lesion? This increases the likelihood of neoplasia or a kerion. Or are there multiple lesions? These may b e due to sterile inflammatory diseases, more aggressive neoplastic disease, or severe infection. The presence of draining tracts in creases the likelihood of foreign bodies, severe bacterial or fungal infection, or sterile inflammatory disease. In a cat with nodules, history taking and clinical exam ination are followed by microscopic eva luat ion of impression smears (if draining tracts are present) and aspirates (in any cat with nodules) (p . 21). In some patients, cytology will reveal an infectious organism or classic neoplastic ce lls and thus a diagnosis. In most patients, cytology will aid in further limiting the list of differential diagnoses, but a biopsy (p . 38) will be necessary to reach a diagnosis . With nodular lesions, a comp lete excision of one or more nodules shou ld be performed. If draining tracts are present and/or cytology indicates possible infection, a tissue culture may be useful as well (p . 43) . The differential diagnoses for feline nodules are listed in Table 2-11 .

100

Table 2-11 Differential Diagnoses, Commonly Affected Sites, and Recommended Diagnostic Tests in a Cat with Nodules DISEASE

COMMONLY AFFECTED SITES

TREATMENT

PROGNOSIS

N eoplasia" "'

Varies with individual neoplastic diseases

Surgical excision and/or tumor specific therapy

Poor to excellent depending on th e individual tumor.

Abscesses (caused by bite wounds or foreign bodies)

Fluctuating nodules most commanly around neck, sho ulders, and tailba se

Surgical drainage, anti bacter ial treatment (p. 118)

G ood

Opp ortun istic mycobacterial infect ion" (ubiquitous, facultativelv pathogen ic organisms such as M?/cobaeteria fQ~ t1~m ,

Nonhealin g ulcerated nodules with draining tract s predom inantIy in the abdom inal or inguinal area (Figures 2-58 and 2-59 ).

Wide surgical excision followed by comb ination anti microbial therapy (p. 131)

Fair wi th appropriate surgica l approach

Upper respiratory, cutaneous, e NS, and ocular signs. Firm swelling over the br idge of the nose (Figure 260) , papules, nodules, ulcers and drainin g tracts. N ose, lips, and claw beds maybe affected.

Ant imycot ic th erapy with azoles and/or amphotericin B (p. 131)

Fair

Finn nodules with draining fistulae (Figure 2-61)

Complete surgical excision, postsurgical antibacterial treatmen t

Fair with complete excision; guarded. if this is not possible.

.

M . chelonei, M . ~gmati$,

.

cause lesions after traumatic implantation into subcutaneous tissue) Crv ptococcosis" (uncomm on infecti on of somet imes immunocompr ornised host with ubiquitous, saprophytic, yeast-like fungus

Gry/?tococcus neoformans) Bacterial pseudomyceroma (nonbranching bacteria such as coagulase-positive Staphylococci implanted by trauma form grains of compact colon ies surrouncled by pyagranu lomatous inflammation; rare disease)

o

--

(p.1 18)

o

N

Table 2-11 continued DISEASE

COMMONLY AFFECTED SITES

TREATMENT

Eumyco tic mycetoma (ubiquitous soil saprophytes cause disease through wound conta mination; rare disease)

No dules with drai nin g tracts and scar tissue. G rains vary in size, shape. and colo r.

Wide surgical excision followed by anti mycotic therapy (p. 13 J ) based on in virro susceptibility testin g.

Fair to guarded depend ing on surgical excision .

Surgical exc ision, combination antibiotic therapy (p. 119)

Fair

Single or multiple, non painful and Feline Leprosy" non prur itic nodules on head and (presumably transmission of an limbs; somet imes ulcers and fistulae : incompletely cha racterized · mycobacte rium that is difficult . are present (Figure 2-62 A and B) · to culture thro ugh bite woun ds · from rats; rare disease in veter i: nary dermato logy)

PROGNOSIS

• Actinobacillosis* , (Ora l commensal aerobic , ActinobaciUus ligneriesii is trau• mat ically implanted, ofte n , through bite wound s; rare dis[ ease in veterinary dermatology)

Thick-walled abscesses of the h ead, mouth, and limbs discharging thick pus with soft yellow gran ules.

Surgical excision or drainage an d lon g-term antibacterial th erapy with strep tomycin, chlorarnphen icol, sod ium iod ide or tetracycl ines (p. 11 8, 121)

G uarded

H istoplasmosis (uncommon infect ion with dimorphic, saprophyt ic soil fungus /-liscoplasrna capsulaturn; very rare disease in vcrerin arv derm atology)

Papules, nodu les, ulcers, and drain ing tracts with concurren t anore xia, weight loss, and fever; dyspnea and ocular disease

Amimycotic therapy with moles, possibly in combination with ampho tericin B (p. 131)

G uarded to grave

Nocardiosis"

Ulcerated nodu les and abscesses, often with dra ining tracts, on the limbs and ventral abd omen

Surgical drainage, antibacterial th erapy based on in vitro susceptibi lity testing.

Guarded

(Nocardia spp. am soil saprophvtes that cause respirarory, cutaneous, or d isseminated infection s; very rare disease in veterinary dermatology)

o w

Phaeohyphomycosis* (wound conta minat ion by ubiqu itous saprophytic fungi with pigmented hyphae; very rare disease in vete rinary dermatology

Often solitary subcutaneo us nodules on nose, trun k, or extre mit ies

Wide surgical excision followed by ant imycotic therapy (p. 131) based on in vitro suscept ibility test ing.

Guarded

Plague (infection with Yersinia pestis by inha lation of organism or through wound contaminat ion or flea bites; very rare disease in veterinary dermato logy) Zoonosis: Spread thro ugh transmission of infected fleas, present ation of infected killed rodents, or direct infect ion!

H igh fever, depression, anorexia, and abscesses typically on the face or limbs in the bubon ic form . Sep ticemic and pneumonic form" also exist.

Flea contro l (p. 136) , draining of abscesses, ant ibacte rial th erapy with tetracycline, strepto rnycin, or ch loramp hen icol (p, 118)

Fair, if recogn ized and treated promptly.

Sporotrichosis" (caused by ubiquitous dimorph ic funga l saprophyte Sporothrix schenkii th at infects wounds; uncomm on disease in veter inary dermato logy) Zoon osis: Tran smission to hum an s th rough contact with an ulcerated wound easily possible !

Multip le nodules or ulcerated plaques on the head, distal limbs, tailba se (Figure 2-63) . Anorexia, lethargy, fever, and depression possible conc urren tly

Antimycot ic th erapy with iodides or azoles (p . 131)

Fair

Ste rile granulomatous and pyogran ulomatous d isease (unknown path ogenesis)

Firm, painless, nonp ruritic dermal papules, plaques, and nodules typ ically on head and pinnae

Doxycycline I N iacinamide (p. 121 ), immunosuppressive the rapy (p. 14 1), may resolve sponta neously

Fair

S terile panniculitis (un known pat hogenesis)

Solitary nodules on vent ral rump

Surgical excision

Good

Table 2-11 continued DISEASE

COMMONLY AFFECTED SITES

TREATMENT

Tuberculosis* (very rare in small animal dermatology; predominant ly respiratory and digestive lesions)

Insid ious ulcers, plaques, and nodules on head, neck, and limbs discharging yellow-green pus with unpleasant odor.

Combination antimicrobial therapy, frequen t euthanasia (pub lic health concerns).

PROGNOSIS

Poor

Figure 2-59 Figu re 2-58 A 5-year-old cas trated

DSH with nod ules and draining rracts resulting from atyp ical myco bacte ria. (Courtesy of Dr. Sonya Betrenay. )

Dra ining tracts due to atyp ical mycobac teria in a J-year-old castrated DS H.

Figure 2-60 Nasal swe lling cau sed by cryptococcosis in a 6- yearo ld female domestic longhair car. (Courtesy of Dr. T hierry Olivry.)

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IJl

Figure 2-61

Figure 2-62A

Pseudo mycetoma in a Persian cat. (Courtesy of Dr. Peter Ihrke.)

Feline leprosy in a DSH. (Courtesy of Dr. Peter Ihrke.)

Figure 2-62B

Figure 2-63

Closeup of feline leprosy in a DSH. (Courtesy of Dr. Peter Ihrke.)

Nasal ulceration in a 2-year-old castrated DSH with sporotrichosis .

Figure 2-64 The Cat with Nodules

~~ ~

1.... - - No microorganisms. otherwis e inconclusive

-

I

-------.1

Diagnostic result

Neutrophils and cocci, otherwise inconclusive

-

Biopsy (p. 38), culture (p. 32)

No resolution

I

106

Resolution

I

I Bacterial infection

The Patient vvith Otitis Externa Otitis externa may be seen wi.th many diseases in conjunctioo with other clinical signs, which are helpful in the formulation of a list of differential diagnoses. This discussion is the approach to the dog with otiti.s externa and no other symptoms. It is important to differentiate between predispos ing, primary, and perpetuating factors in the pathogenesis of otitis externa. Predisposing factors are iodependent from the underlying disease and alone will not cause disease, but will facilitate the pathologic process . Conformation, including dense hair in the ear canal, a Lo ng and narrow ea r canal, pendulous ears, and climate-re18ted seasonal factors such as iocreased remperature and humidity are exa mples of predisposing factors. Complicating factors occur only after the primary pathologic process has begun, but continue to be a problem after the primary disease has been successfu lly identified and treated. Examples are otitis media, bacterial or fuogal iofections, and chronic proliferative changes due to inflammation . These complicating factors nee d to be treated independe ntly. The most common primary factors are listed in T ab le 2-12. Key Questions ./ HowaLd was this patient when clinical signs were first recognized? (p.3) ./ Is the disease seasonal ? (p. 3) ./ What do yOll feed the aninl.al? Was a special diet used in the past? (p. 7) ./ Are there any other animals in the household? (p. 8) ./ Was the disease treated before? If so, which drugs were used and how successful was treatment! (p. 8) ./ When was the last medication given? (p . 9)

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Table 2-12 Differential Diagnoses, Important Clinical Clues, Recommended Diagnostic Tests, Treatment Options, and Prognosis in a Patient with Otitis Externa DISEASE

COMMENTS

DIAGNOSTIC TESTS

TREATMENT

PROGNOSIS

A topy* (hypersensi tivity to ae roallergens such as po llens , h ouse d ust m ite s, or mold spores). (Figur e 2-65)

In some patients a seasonal co nd ition; unilateral otit is ex tern a may be cau sed by atopy

Diagn osis based o n history, physical ex am in at io n , and ru ling out d ifferen tial d iagnoses. In trad ermal skin test or serum test for allergen specific IgE (p . 42 ) identify offending allerge ns and all ow fo rmul at io n of immunoth e rapy.

Allergen- specific immunetherapy (p. 123) , antihi stamines (p , 125).essent ial fat ty acids (p, 128), glucocorti co ids (p. 129), ropical glucoc orr icoids.

G ood for well-b eing of the pa t ie n t with continued manageme nt, guarded for c ure .

Otodectes cynoti.l infesta-

Coffee grounds appearance of debris in the ear canals

Otoscopic examination. Microscopic evaluation of debris from ear swabs suspended in mineral oil; rniticidal treatment trial (p. 49)

Antiparasitic agents such as iverrnecrin (p. 133) systemi cally, although many patients will respond to rapical miticidal rherapy

Excellent

foreign body

Typically unilareral and of acute onset

Otoscopic examination

Removal

Excellent

Scabies (a highly contagious disease caused by Sarcoptes scobiei var. canis in dogs and Notoedres cad in cars)

Edge s and lateral aspects of pinnae affected as well as (or worse than) the canal (Figure 2-66).

Superficial skin scrapings (p. 26), sarcoptes treatment trial (p. 49).

Antiparasiric agents (p. 133)

Excellent

Elimination diet (p. 46)

Avoidance, anuhisramines (p. 125), essential fatty acids (p. 118), gluc ocorricoids (p. 129), topical glucocorticolds.

Excellent, if offending protein(s) is (are) idenrified and avoided; otherwise (air with connnLied management. Poor chance of cur e.

tion (very common cause, particularly in young anirnals and cats)

Unilateral otitis cxterna Food adverse reaction (rnav or may not be aller- maybe seen with rood gic; commonly a reaction adverse reactions against a protein, rarely an add itive; clinically ind istinguishable from atopy)

Hyperadrenocorticism* (spontaneous or idiopathic. The spontaneous form is an excessive production of glucocorticoids either due to a microadenoma or macroadenoma of the pituitary gland (PDH, 85%) or due to adrenocortical neoplasms in 15%)

Subrle clinical signs may be ove rlooked (see table 2-5). Complete response to thera py of seconda ry ear infect ion

In ner surface of pinnae typiPemphigus foliaceus* cally worse than can als (immune-mediated skin (Figure 2-67) disease characterized by intraep idermal pustule forrnation due to pemphigus antibodies against antigens in the interce llular connections. Ma'( be dtll%" induced or paraneoplast ic ) Neoplasia* (ceruminous gland adenomas and adenoca rcinomas-both types in cats, the former more common in dogs)

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\.0

Unilateral, older an imals

Serum biochemistry (SAP t t , cholesterol t. ALT t. glucose t, urea ~), hemograms (leukocytos is, neutrophili a, lymphopenia and eosinopenia), urinalysis (specific gravity ~, cortisol.creat inine ratio t), radiographs (hepatomegaly, osteoporosis, miner alization of adrena l glan ds), lowdose dexamethasone suppression test, ACTH assays, ultrasonograph y (adrenal gland size t), ACTH srimulation test

Iatrogenic form: discontin ue glucocorticoid adminisrration. Idiopathic form: o,p'DOD (rnitotane), ketocon azole for PDB (p. 13I), surgical removal of affected gland for adrenocortical neop lasia

Approx imately 60% of dogs with adrenal tumors were reported to survive adrenalecto my and the postoperative period. The average life expectancy was 36 months. Ad renal adenocarcinomas have a better prognosis than adenomas. The life span of dogs with PDH treated medically averaged 30 months with some dogs living longer than 10 years and others on ly days.

Cytology (p. 21), biopsy (p. 38)

Immunosuppression (p.141)

Fair with appropriate treatmen t, poor for cure (except druginduced pemph igus)

Otoscopic examination

Surgical excision (vertica l or complete ablation of the ear canal)

G ood, if completely excised and no me tastases

o

Table 2-12 continued DISEASE

Hypoth yroidism (lymphocytic thyroiditis, presumablv auroirnmune ,

or idiopathic th yroid necrosis which may be end-stage lymphocyric th vroiditis)

.

COMMONLY A FFECTED S ITES

Subtle other cIinical signs (nay be overlooked (see Table 2-5). Complete respon se to therapy of secondary ear infecti on

Idiopath ic seborrhea" Excessive wax formation even (primary kerat inization wirh topical medication . defect as autoso mal recessive trait with decreased epidermal cell renewal time and thu s hyperproliferarion of epidermis. sebaceous glands. and follicular infundibulum secondary to inflammation. endocr ine disease, or nutrition al deficiencies) . --

DIAGNOSTIC TESTS

TREATM ENT

Serum biochemistry (SAP i , cholesterol t , ALT i ), hemograms (anemia) , th yroid tests (free T4, tot al T4 , free T 4 by equilibrium dialysis, TSH assays, TSH stimulation test, TRH stimularion test)

Hormone replacement therapy with levotlwroxine (p. 144)

Biopsy [p, 38 )

Ear cleaners, retin oids, cor ticoste roids

PROGNOSIS

Good , al though not all patients stay in com plete and consran t remission despite adequate supplernentation .

Fair to guarde d for well-bei ng; poor for cure

Figure 2-65

Figure 2-66

Pinnal erythema, scaling, and erosions in a West Highland White Terrier with atopy (Courtesy of Dr. Sonya Bettenay).

Pinnal scaling and crusting in a male Great Dane with scabies (Courtesy of Dr. Sonya Bettenay).

Figure 2-67 Pinnal otitis in a 2-year-old, male Whippet with pemphigus foliaceus (Courtesy of Dr. Son ya Benenay) .

Figure 2-68 Identification of the Primary Disease in the Patient with Otitis Extema

Inflammation and debris

r Young animal

I

1

Older animal

Thyroid testing. uri ne cortisol creatinine ratio post antimicrobial treatment (p. 118)

Depending on patient and owner Nondiagnostic

, Diagnostic

I

Further testing or treatment as indicated Remission

Relapse

No change

I.

Monitoring -

112

Relapse later on

Cytology is essential in any dog or cat with otitis externa; examination must be separate in the left and right ear canals 4 kg. 0 .4 ml (0) > 5 kg, 1 rnl (0) 5-10 kg, 25 ml (D ) 10 - 25 kg, 4 rnl (D ) > 25 kg

P t ya lism , t re mo rs, atax ia, vo m it in g, de pression , hype ra est hesia , se izures, d ysp nea

Use q 24-72 h (D , C )

Pt ya lism, trem ors,

Use q 3-] 0 da ys (D)

Selamec rin

15 mg, 30 mg, 4 5 mg, 60 mg, 120 mg, and 240 mg tubes.

Imidacloprid

Flea -bi te h ypersensi9 . 1% so lut io n (0 .4 rnl , Freq ue nt sha mp oo ther ap y or water expo - t ivit y 0 .8 rnl, 1 rnl, 2.5 rul , su re will sign ifica n tly 4 rnl ru bes) decrease efficacy. So lvent ma y d isco lor lacqu er o n furn itu re.

Pyrerh rin

S prays and pow de rs at 0.05-0.2%

Re pe lle nt as we ll as Flea-bi te h vpersensiad ulric ide . Lo w toxi c i- t iv it y t y poten tia l, sa livat ion in cats

Perrneth rin

Sprays, spot-e ns and sha mpoos at 0.2-2%

Repellent as well as C a n in e flea-b ite ad ult ic ide. Lo w to xicity h ype rsensiti vit y in dogs. Not to be used in cats'

Flea- b ite hypersensitivitv, O todectes cyn otis in festat ion, scab ies , heartworm prevention, roundworm, and hook wor m infes ta t ion s

Spray: 4-6 ml/kg q 2-12 weeks (8- 12 pu mps using the 100 ml bottle, 2-4 pumps using the 2S0-ml bottle ). (D, C ) Spa r-on: App lv o nce

ruonrhlv

atax ia, vo m it in g,

depressio n, h yperaesrh esia, seizures, d yspn ea

Insect Control Trials and Individual Management of Patients with Flea-bite Hypersensitivity Flea control trials ./ Treatment recommendations will vary significantly with indi~ vidual situations. Confirmed flea~bite hypersensitivity, suspected f1ea~bite h ypersensitivity, or pets that show no sign of discomfort, but have some fleas, are treated very differently . ./ Reasonably safe and effective products are available (Table 3~7). As veterinarians, we are in the best position to advise clients on a flea-control program tailored to their specific needs that considers their personalit y and life style as well as their pet's little peculiarities.

h A major reason for failure of flea control programs is owner compliance. They are either unwilling, not educated pwperly, too careless, or simply not physically able to do what we ask them to do for whatever reason. Choosing th.e right protocol and educating owners properly, taking th.e time and possibly using nursing staff, brochures, and message boards will greatly increase your chance of success. ~ With all topical products, the first application should be administered in the clinic by the veterinarian or the veterinary technician/nurse to demonstrate the correct procedure to the owner.

./ Another reason fo r failure may be resistance of the organism to the products used. Resistance will always develop to any prod~ uct, the question is thus not if, but rather when. In essence, we speed up evolution and create resistant fleas by putting pressure on the population when using products for flea control. However, there are ways to delay this development of resistance. The first possibility is to combine different flea products, as it: is much less likely that an individual flea gets resistant to two drugs at the same time. This approach is called integrated flea contwl and is becoming more popular all over the world . The second possib ility is to switch products quickly when signs of resistance occur and kill the resistant flea with another effective product before it has time to multiply in big numbers. 136

./ Suspected flea-bite hypersensitivity: A ggressive flea control is needed for 4 t o 6 weeks. If there is n o i.mprovement, we most like ly do n ot deal with flea-bite hypersensitivity. Wi t h s ignificant improvement or remission, we es t ab lished a di agnos is and need to discuss long-term strategies with that particular owne r. In such a trial, w e usually recommend the fr eq ue nt use of a n a dulticide in combination with an insec t growth regulator in the env ironment t o quickly lower the flea pressure (Tab les 3-8 and 3-9) . ./ Confinned flea-bite hypersensitivity: Id ea lly, we recommend a n insect g ro wth regulator/ins ec t development inhibito r o n a pennanent basis (systemically, t o pica ll y or in the e nvironme nt) and a n ad ultic ide as n ee ded (Tables 3-8 a nd 3-9 ) . The sec o nd op t io n is a n adulticide only, in which case we n eed to s witch products very quickly a t the first s ign of r es istance. However, as ad ulticid es a re tapered slowly to identify t h e lo n ges t possible inte rval in b e tween app lications, rec urrences m a y indicate insufficient frequency of application rather than resistance . ./ No flea-bite hypersensitivity present: In these cases, w e do n ot recommend flea control becau se permanent fl ea exp os ure m.ay b e less likel y to induce fle a-b ite h yp e rse n s it ivity t h a n offand -on fl ea concr o l by an o wner who is not pressed into complia nc e by a n itc hy p e r. If the client does want to start so m e so rt of fl ea control, insect g rowth reg ul a t ors o r d evelo pme nt inhibitors are r ecom m e nd ed.

Mosquito-bite trial The safest a nd m ost thoroug h mosqui to-b ite tri a l in cats with papules a nd crusted papules o n n ose, pinnae o r foot pa d s is to keep the patient indoors fo r 2 weeks. When th ere is n o expos ure to mosquitoes, the disease reg r esses r ap idly_ However, in cats u sed to o utdoo rs thi~ option m ay n o t be viable . A lte rnatively, expos ure is decrease d when o utd oor act ivi t ies a r e limited and cats are trained t o c o m e in before dawn by feeding them in th e la te a fternoon. In add iti on, a mosquito r epe lle nt safe for u se in c a ts such as pyre thrin sp r ay m ay b e app lie d by wett ing a cl o th a nd wiping the feet and h ea d d a ily before t h e cat goes o u t.

137

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Table 3-8 Administration, Advantages, and Disadvantages of Selected Flea Control Products DRUG

ADMINISTRATION

ADVANTAGES

DISADVANTAGES

COMMENTS

Foggers are more convenient but do not

Insect growth regulators/development inhibitors Indoors: spray q 12 m. Outdoors: Spar treatmenr of allergic pet 's favorite spars q 6-12 m in dry environments.

Comparatively safe and effective, rapid onset of act ion

Work-intensive

Lufenuron

10-15 mg/kg q 30 d orally (D) , 25-50 mgjkg SC q6m(C) .

Convenient, safest environmentally

Expensive in multi-pet hou seholds, lag period of several weeks to months.

Indi cated in house -holds with few pers and no visits from an imals witho ut thorough flea control.

Meth oprene or Pvriproxifcn

Indoor spray q 6 m

Comparativel y safe and effective, rapid on set of action.

Work -intensive

Foggers are more convenient, but do not cover more than 2 room s/can. The insecticide stays on shelves and furniture, but areas underneath furniture are nor covered ! Spra ys are less convenient and more work intensive, but insecticide is deposued only where needed . Use in all rooms with pet access ' Carpeted areas, crevices, and corners, as well as are as underneath furniture most important. Indicated with frequent visiting anim als not on flea control as well as ar the start of an insect control trial.

Fenoxvcarb

cover more than 2 rooms/can. The insecticide stays on shelves and furniture, but area s underneath furniture ate not covered ' Sprays 3re less convenient and more workintensive, but insecticide is de posited only where needed. Use in all room s with pet acce ss' Carpeted area s, crev ices, and comers as well as area s underneath furniture are most important. Indi cated with frequent visitin g animals not on flea control as well as at the start of an insect -control tria l.

Adulticides Fipron il

0 .29 g/ lOO m l, 10-1 5 mg/ kg as a spray d isrrihuted over th e who le body q 2-8 week, spo t-on q 2-8 week

Water-proof ( but n ot sh a mpo o proof") . co nven ien t, because used o n ly e very 2-4 wee ks

No re pelling ac tion , ex pe ns ive in large an imals, vi ab le egg produc tio n pos sible .

Spray n eeds to be app lied ca refully, covering the ani mal's who le body. Spot-on formulatio n easier to apply, bu t less effec t ive . Ad m in iste r o utdoors or in well-ve nt ilated a rea d ue to Strong smell du ring first minu tes. Sha mpoo on ly 2 da ys before n ew app licat ion .

Imidaclc prid

100 mg/m l

Conv e n ie nt , bec au se used on ly e ve ry 2-4 wee ks, easy ro app ly

N o t wate r proof, n o repellingviab le egg prod uc t ion possible .

Sh a mpoo o nl y 2 days before ne w app lica t ion . Sw imm ing or roaming in ra in y wea ther n ot rec omme nd ed .

N ite n pyra m

Ta blets q 1-2 d o r as n eeded

C o nv e n ien t, ra pid o nse t of act ion , sa fe

Flea needs to b ite an imal to d ie, o n ly effec t ive for less than o ne day

May be given da ily with no adverse effects. Part icularly useful for pro ph ylactic adrnin istr a t ion in an ima ls on lufenuro n di rec tl y befor e anticipated exposure in shows or visits.

Repels ins ec ts, q uick knock -o ut

Wo rk-intensive, rare but po ssible to xiciti es, de pend ing o n prod uc t an d patie nt; dail y-to monthl y ap plica t ion

Soak an imal with sprays (pressure pump sprays may be useful for bigger ur lo ng-h aired dogs).

Pvrethr in

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~

Table 3-8 continued DRUG

ADMINISTRATION

ADVANTAGES

DISADVANTAG ES

COMM ENTS

Permethrin

744 mg in I ml as a spoton for dogs < 15 kg, 1488 mg in 2 ml for dogs> 15 kg. Do not use in cats.

Repelling action, qui ck knock-out.

Work-intensive, rare but possible toxicities, depending on product and patient; daily-tomonthly application

Soak animal with sprays (pr essure pump sprays may be useful for b igger or longhaired dogs) .

Selamectin

6- 12 mg/kg monthly as a spot-on

Easy to use, cosmetically appealing, safe

Too new to comment at time of writing

Too new to comment at time of writing.

Table 3-9 Application of Selected Flea Products in Patients with Confirmed versus Suspected Flea-bite Hypersensitivity CONFIRMED

Fipronil spo t-on

q 2-4 weeks

Fipronil spray

q 4 - 12 weeks

q 7-14 d for 4-6 weeks"

Imidacloprid spot-on

q 4 weeks

q 7-14 d for 4-6 week s"

N ite npyram

In additi on to lufenuron, when pa t ient shows clinical signs or before suspected exp osure

q 1-2 d for 4-6 weeks"

Pennerhrin spar-on

q 4 weeks

Nor used for insect control trials

Permerhrin spray

Varying depending on individual product lip to q 7-14 d

Varying depending on indiv idual product up to q 2-3 d for 4-6 weeks"

Pyrerhrin spray

Varying depend ing on indiv idual product up to q 7-14 d

Varying depending on individual product up to q 2-3 d for 4-6 weeks"

Selamecrin

q 4 week

q 14 d for 4-6 weels"

* In

FLEA-BITE HVPERSENSITIVlTY*

SUSPECTED FLEA-BITE HYPERSENSITIVITY

DRUG

Nor used for insect control trials

an y flea control t rial adulricides are combined wirh an insecr growrh regulator used in rhe environment ar rhe beginning

or the trial.

Immunosuppressive Therapy fi7" Before YOLl think abollt immunosuppressive therapy you must be sure about your diagnosis. It can be very dangerous for your pati.ent to start imm.unosuppressive drugs based only on history and clinical examination as a confirmation of the diagnosis of immune~mediated skin disease. If the animal has an infectious disease (fungal, bacterial, or parasitic), it can rapidly deteriorate and even die. There is no place for trial therapy in immunemediated disease (except in the case of a patient facing euthanasia otherwise). t} Patients with

immune~mediated skin disease commonly have

secondary infections that need to be identified and treated. In patients with mild-to-moderate disease, 1 start ant imicrobia l therapy 3 weeks before immunosuppressive therapy to eva lu ate how many of the clinical signs are due to the infection and how many are due to the immune~mediated disease . In cases of seve re clinical disease, however, treatment of infection and of the immune-mediated disease should be started concurrently.

h It is impossible to give YOll a good general purpose recipe for immunosuppression. Every dog or cat reacts differently to each of the drugs mentioned later in this section and you have to individualize treatment for each patient. Immunosuppression is a technique requiring instinct, sensitivity, and experience as well as theoretic knowledge that is beyond the scope of this text. There are, however, certain generalizations as well as certain starting dosages and ranges . ./ Probably the best way is to start using one preferred drug, then, if your approach fails, refer the patient and learn from the way the specialist treats it. After you are familiar with that new drug, YOll add anothe r one to your repertoire and use both of them and so on . ./ The doses mentioned in Table 3-10 are starting doses that are tapered as soon as possible to the smallest effective dose.

141

./ Taper the drug once the patient is in clinical remission or if adverse effects are intolerable. In a patient with severe adverse effects and concurrent clinical signs of ac tive disease, new drugs need to be added at the same time.

fi:',<Monitoring, as described in Table 3-10, is essential. 1 only cOlnprolnise on Inonitoring standards because of financial considerations in patients facing euthanasia otherwise! ./ Some dogs will have seasonal relapses. This mechanism is currently not understood. If a well-controlled patient suddenly seems to relapse, always check for demodicosis and fungal or bactertal infections first. Rather than a flare-up of the immune-mediated disease you may be encountering a problem secondary to your treatme nt. These patients are immunosuppressed and thus easily may b e affected by infectious diseases l Increasing the dose of the immunosuppressive drug may not always be a good idea.

142

Table 3-10 Drugs Used in Immunosuppressive Therapy

+:> w

MONITORING

FORMULATION

COMMENTS

ADVERSE EFFECTS

Prednisone/ Predniso lone

5 mg. 20 mg, 25 mg. 50 mg tablets

Rapid onset of action. inexpens ive. response rare approx imate ly 50% , high rate of adverse effects

Polyuria, polydipsia, 1-2 mg/kg q 12 h (0) , } -4 mg/kg q 12 h (C) polyphagia, lerh argy. infections, muscle wastin g, panti ng, exercise inrolerance, calcinosis cutis

U rinal ysis an d urin e cultures q 6 mo. possibly biochemistry panels and ACT I-J st imulat ion tests q 6- 12 mo

Azarhioprine*

25 rng ta blets, 50 mg tab lets

Lag period of several weeks in dogs. Should n ot be used in catsl!l Further reading is recommended before using thi s drug.

Vomiting, diarrhea (less 2 mg/kg or 50 mg/m2 common . if administered q 24 h (D) divided into 2 daily doses), bone marrow suppression, idiosyncratic hepatotoxicitv (possibly peracute)

Compl et e blood counts at 0 , 1, 2, 4, 8, 12 wk and the n every 3-6 rno, hOSSibly serum bioc emistry concurrently, parricularly during the first 1-2 mo.

Chlorambucil*

2 rug, 5 mg tablets

Long lag period (4-8 wk). Vomitin g, diar rhea, bon e 0.1 -0 .2 mg/kg q 24 h (D, C) Safest imrnunosuppressive marrow suppre ssion . agent, may be used in cats. Further reading is recommended before using this drug.

Co mplete blood counts at 0, I, 2, 4, 8, 12 wk and then every 3-6 mo

Long lag period (6- 12 wk). May be used in cars. Some an imals go into complete remission and cessation of therapy may be possible. Furth er reading is recommended before using th is drug.

Complete blood counts and urinalvsis at 1, 2, 4. 8, 12 wk and th en every 3-6 mo. Se rum bioche rnistrv month ly inirially, then every 3-6 mo.

Aurothioglucose* 50 mg/ml suspension

Bon e marrow suppression , occas ional cutaneo us eruptions and proteinuria

DOSE

DOG DOSE (D) DOSE (C)

DRUG

CAT

1 mg/kg q 7 d 1M (D,C) after a test dose of 1 mg/animal. Tapering to q 2 wk, 3 wk, 4 wk after remission ach ieved

a,

Treatment of Alopecia due to Hormonal Diseases and Follicular Dysplasia (Table 3-11) . Table 3-11 Selected Drugs Used in the Treatment of Endocrine Disorders with Cutaneous Symptoms DRUG

DOSE

o ,p '-DDD* (mirotane)

DOG DOSE (D) CAT DOSE (e)

INDICATIONS

ADVERSE EFFECTS

25 mg/kg q 12 h dur ing induction (5-14 d), same dose q 12 hon 2 CORsecutive days of each week as m ain tenance. Length of induction determine d by wate r int ake, food intake, and AcrH stimulat ion test. (D, C)

Idiopathic hyperadren ocorticism, adrenal sex hormone imbalance (I do not recommend the drug for th is latter d isease) . Further reading is recom mended prior to using th is drug.

Le thargy, ataxia, vomiting, d iarrhea, anorex ia.

Levothvroxine

20 I-tg/kg q 12 h . If patient condition is well controlled, medication may be changed to once daily at double dose. (D, C)

Hypothyroidism

Polydipsia, polyuria , nervousness, aggressiveness, panting, diarrh ea , tachycardia, pyrexia, pruritus, heart failure in dogs with cardiac disease, exacerbation of adrenal crisis in dogs with hypoadrenocorticism

Testosterone

0.5-1 mg/kg (up to a maximal dose of 30 rng) q 24 h orally (D, C)

Aggressive behavior, greasy haircoat, prostatic hypertrophy, hepatotoxicity

Estrogen

0.02 mgjkg q 48 h for 6-12 wk oral- Estrogen-responsive dermatosis Iy or q 24 h for 3 wk, then 1 wk off, then repeat cycle (D).

Estrus induction, bone marrow suppression, hepatoroxicirv, pyometra, spontaneous abortion

Melatonin

3-6 mg q 12-24 h for 2-3 rna (D)

Cyclic follicular dysplasia, follicular dysplasia, alopecia.

Abscess formation with injection of repository ca psules.

Gro wth hormone"

0.1 IU/kg q 56 h for 6 wk (D)

Adrenal sex hormone imbalance, growt h-hormone responsive disease (I do not recommend treatmenr with this drug).

Anaphylaxi s, ac romega ly, diabetes me llitus

Appendices A. Breed Predilections Abyssinian cat

Ceruminous otitis extenla Psychogenic a lopecia

Airedale

Adult-on set demodicosis

AkLta

Pemphigus fo liaceus Sebaceous adenitis Uveode nn ato log ic s)'ll.drome

Basse t H o und

Atopy Intertrigo Malassezia de nnatiti s Sebo rrhea

Beagle

Atopy Demodicos is IgA defic ie n cy

Belgian Te rvure n

Vitiligo

Bo rde r Co llie

Systemic lupus erythematosus

Borzoi

Hypo thyroidism

Boston Terrier

Atopy Demodicosis Intertrigo

Boxer

Atopy Cyclic follicular dysplasia Demodicosis Hype radrenoco rticism Muzzle a nd/o r pedal bacterial funm c ulosis

Bullmastiff

Bacte ria l furunc ulosis

Bullte rrier

Atopy Acrodermatitis Bacteria l furunculosis Solar d erm a titis

Cairn T erri e r

Atopy

Ches';peake Bay Retriever Atopy Ch ihuahua

Demodicosis

Chow C h ow

Adrena l sex hormone abnorrnalities Pemphig us foli aceus Demodicosis Hyposomatotfopism Hypothyroidism

Collie

Dermato myosit is

145

Lupus erythematosus Pemphigus erythematosus

146

Curly-coated Retriever

Follicular dysplasia

Dachshund

Bacterial pyoderma Color dilution. alopecia Hyperadrenocorticism Hypothyroidism Juvenile ce lluli t is Malassezia dermatitis Pattern alopecia Pinnal vasculitis Sterile pyogranulomatous dermatitis Sterile nodular panniculitis

Dalmatian

Atopy Demodicosis Solar dermatitis

Dobennan

Acral lick dermatitis Bacterial pyodenna Color dilution alopecia Demodicosis Drug reaction (particularly against sulfonarn.ides) Follicula r d ysplasia Hyporhyroidism Vitiligo

English Bulldog

Atopy Bacterial pyoderma Cyclic follicular dysplasia Demodicosis Intertrigo Hypothyroidism Malassezia dermatitis Sterile pyogranuloma syndrome

German Shepherd

Atopy Bacte ria l pyoderma Ear tip fly dermatitis Eosinophilic funmculosis Flea-bite hypersensitivity Food adverse reaction Idiopathic onychomadesis Mucocutaneous bacterial pyoderma Pemphigus erythematosus Pituitary dwarfism Systetn ic lupus eryth ematosus Tarsal fistulae Vitiligo

Golden Retriever

Acral lick dennatitis Atopy Bacterial pyoderma Hypothyroidism ) uvenile cellulitis Nasal hypopigmentation ("Dudley nose") Pyotraumatic dermatitis

Gordon S etter

Atopy Hypothyroidism

Great Dan e

Acra l lick dermatitis Bacte ria l pyoderma Callus fonn a tion Demodicos is Hypothyroidism

Great PYl"enees

Demodicos is Pyorrauma tic dermatitis

Irish Setter

Atopy Colo r dilution alopecia H y po thyroidism

Irish W ater Spaniel

Follicula r dysplasia

Jac k Russel T~rrier

Atopy Demodicosis

Keesh ond

Alopecia X due to sex h o rmo n e imbaLa n ces Hyposomatotropism Hypothyroidism

Labrador Retriever

Acral lick dermatitis Atopy Bacteria l pyodenna Food adverse reactio n P yotraumatic clennatitis Seborrhea

Lhasa Apso

Atopy Malassezia d e rmatit is

Malamute

Zinc-responsive dennatitis

N ewfo undland

Bacterial pyoderma Pyotraumatic derm.atitis

Old English Sheepdog

Atopy Demodicosis

Pekingese

Intertrigo

Persian Ca t

CheyletielLosis Dermatoph ytos is Intertrigo Seborrhea

Po inter

AcraL mutil ation Demodicosis Hereditary lupo id dermatosis

Pomeranian

Adrenal sex h ormon e a bnormalities H yposoma to tropism

Pood le

Hyperadre n ocortic ism Hypothyro idism Inj ection reactions Sebaceous ad enitis (Standard)

Porwguese Water Dog

Fo llicula r dysplasia 147

148

Pug

Atopy Intertrigo

Rhodesian Ridgeback

Dermoid sinus

Rortweiler

Bacterial pyodenna Vasculitis Vitiligo

Samoyed

Sebaceous adenitis

Schipperke

Pemphigus foliaceus

Scottish Terrier

Atopy

Shar-pei

Atopy Bacterial pyoderma Demodicosis Food adverse reaction Hyporhyroidism IgA defICiency Intertrigo Mucinosis

Schnauzer

Atopy Aurotrichia Hyporhyroidism Schnauzer comedo syndrome Superficial suppurative necrolytic Den-narieis

Shetland Sheepdog

Dermatomyositis Lupus erythematosus

Shi-Tzu

AtOpy

Siamese Car

Food adverse reaction H yporrichos is Periocular leukotrichia Vitiligo

Siberian Husky

EosinophilLc furunculosis Follicular dysplasia Zinc-responsive dermatitis Atopy

Spanieb

Food adverse reaction Hypothyroid ism Idiopathic onychomadesis Intertrigo Malassezia dermatitis Psoriasifonn-lichenoid dermatosis (English Springer Spaniel) Seborrhea

St. Bernard

Acral lick dermatitis Bacterial pyoderma

Viszla

Sebaceous adenitis

Weimarcmer

Sterile pyogranulomatous syndrome

West High land White T errier

A topy Fo o d a dverse rea ct ion M al assezia d errua rit is

Sebo rrh ea Yorkshire T errier

Co lo r dilution a lo pec ia Injec tion rea c t io n s Trac ti o n a lope c ia

B. Questionnaire What is the main problem? A t what age wa s this cond ition first noti c ed ? Has ther e e ver b een an y previ ous de rmatitis? 0 Yes

_ _ 0 No

Do the symptoms vary? If the derm a t it is h as b ee n present fo r so me time a re the sympto m s worse in: o spring? 0 su m mer ? 0 a u tumn? 0 wi nter? Are the sym p t o ms p resent all year round ? 0 Yes 0 No If yes, wou ld there b e a ti m e o f no sy mp tom s a t so me stage? 0 Yes 0 N o What ( if an yth in g ) causes a worsening o f sym p to ms 7 _ W h a t h el ps ? _ Home details: D o you h av e an y o th e r pets - and if so h ow m any? _ ca t s _dogs _ b ird s _ o th.e r Do you know of an y relative o f this p e t t h at has skin problems? D Yes 0 N o Does any human in the h ouse h ave skin p rob lems ? 0 Yes 0 No W h.ere d o es th is pet sle ep ? H av e there been a n y other illn e sse s ? Bathing and fleas: Does b a thing: 0 h el p G worsen 0 make n o diffe rence H o w ofte n do you prefer to b a th your pet? 0 weekly 0 month ly 0 rarely Wh.en w as the last t ime a fl ea was seen o n this p et? _ _ othe r p e ts? _ _ What is the cu rre n t fle a treatm ent on th is pet ? _ Is fl ea tre atment used o n o t her pets ? Medication: If p revious med ic ations h ave b ee n us ed, d o you know what t h ey were ? D Yes 0 N o If yes, were they : 0 sha m po o s 0 rin ses C in jec ti o n s 0 tab lets 0 ointments Last tablet g iven (date) : R e sp onse: 0 none 0 so me 0 go od Last in je c t io n given: (d at e ) : Resp onse : 0 none 0 some 0 good Is your d og on h e art w o rm tab lets ? 0 No 0 Yes : 0 d a ily 0 monthly

149

Diet: Wnat do you nonna lly fee d your p et? 0 cans If meat - wh ich types?

0 dry

Any other foods? (eg ., vitamins, toast , b isc uits) Have you ever fed a special d iet? D N a 0 Yes: What?

0 tab le scraps

Q

m ea t _ _

Symptoms? H ave any of t he following been observed ? D so res D scabs D dandruff D hair loss D odor D h ives D red n ess o sweat ing 0 ear problems 0 watery eyes 0 heat o we ight lo ss D we ight gain 0 vom it ing 0 dia rrhea 0 tiredness D d e pressio n. D in cre ased appeti te D increased th irst Does your per: D rub at the face 0 l ick or chew the paws o scratch at the sides D ro ll o n the b a ck 0 bi te at the tail area o lick the stomach area D sneeze D snort 0 wheeze o t he r? _ What do you think cou ld be the cause of the problem? _

150

Recommended Readings Bonagura JD. Ed . Kirk's Current Veterinary Therapy (XII and XIII ). Philadelphia, WB Saunders, 1995 and 2000. Campbell KL. Ed. The Veterinary Clinics of North America~Small Animal Practice: Dermatology, Vol. 29 (6). Philadelphia, WB Saunders, 1995 . Feldman EC, Nelson RW. Canine and Feline Endocrinology and Reproduction . 2nd Ed. Philadelphia, WB Saunders, 1996. Greene CEo Infectious Diseases of the Dog and Cat. 2nd Ed. Philadelphia, WB Saunders, 1998. Griffen CE, Kwochka KW, MacDonald JM. Eds. Current Veterinary Dermatology. St. Louis, Mosby, 1993. Kunkle G. Ed . The Veterinary Clinics of North America~Small Animal Practice: Feline Dermatology, Vol. 25 (4) . Philadelphia, WB Saunders, 1995. Kwochka KW, Willemse T, von Tscharnel' C. Eds. Advances in Veterinary Dermatology, Volume 3. Oxford, Butterworth Heinemann, 1998. Locke PH, Harvey RG, Mason IS. Handbook of Small Animal Dermatology. Oxford, Pergamon, 1995. Moriello KA, Mason IS. Handbook of Small Animal Dermatology. Oxford, Pergamon, 1995. Ogilvie GK, Moore AS. Managing the Veterinary Cancer Patient: A Practice Manual. Trenton, Veterinary Learning Systems, 1995.

Plumb DC. Veterinary Drug Handbook. 3rd Ed. White Bear Lake, Pharma Vet Publishing, 1999. Reedy RM, Miller WH, Willemse T. Allergic Skin Diseases of Dogs and Cats . 2nd Ed. Philadelphia, WB Saunders, 1997 . Scott DW, Miller WH, Griffin CEo Small Animal Dermatology . 5th Ed. Philadelphia, WB Saunders, 1995 .

151

Dermatology for the Small Animal Practitioner

The quick reference manual you need for Dermatology - Practical guidelines for diagnosis and treatment of the skin diseases that you see every day in practice. - Over 115 Color illustrations integrated with the text for easy identification of lesions. Dr. mecl.vet., _ C . k MACVSc Di ACVD are f u 11 y desi esrgrie d ta bl es £lor qU1C access FACVSc ' P ' t o important diagnostic and treatment information. Ralf S. Mueller

- Formulary of dermatologic drugs and preparations. - Provides quick identification of rare and complicated dermatologic tests. - Clear, step by step descriptions of commonly performed diagnostic tests. - User friendly, consistent design which helps the reader focus on the really important information. - Companion CD~ROM provided which contains the book plus an expanded library of color illustrations for instant search and retrieval of information.

Forthcoming titles in the Made Easy Series for the Small Animal Practitioner: Thoracic Radiology· Transfusion Medicine· Endocrinology • Echocardiography

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TNM