April 2008 Dermatology Edmund J. Rosser Jr., DVM, Diplomate ACVD Michigan State University Diagnosis And Treatment of Food Allergy in Dogs and Cats Prospective Clinical Evaluation of Food Allergic Dogs and Cats Previous recommendation of a 3 week elimination diet trial was empirical Initial recommendation in this study was to feed a home-cooked restricted diet for 60 days In several instances the results were equivocal after 60 days and the diet was fed an additional 30 days. Data Collected Time elapsed before maximal clinical response on diet Time elapsed before return of initial clinical signs when fed previous diet Age, breed, sex, clinical signs Responsiveness to glucocorticoids Concurrent disease conditions Final treatment diets Diets Fed Formulated based on known past exposure Avoided any previously consumed foods Consisted of home cooked foods Canine diets Protein sources - lamb, venison, moose, elk, rabbit, duck, goose, goat, ostrich, emu, alligator, kangaroo, pinto beans Carbohydrate source - rice, potatoes, sweet potatoes (yams), rutabagas, oats, barley Feline diets Protein sources - rabbit, venison, lamb, duck, goose, ostrich, emu Carbohydrate source - green peas, rarely rice Results - Canine - Time elapsed before maximal clinical response 1-3 weeks - 13 dogs 4-6 weeks - 25 dogs 7-8 weeks - 10 dogs 9-10 weeks - 3 dogs Results - Feline - Time elapsed before maximal clinical response 1-3 weeks - 4 cats 4-6 weeks - 7 cats 7 weeks - 1 cat, 9 weeks - 1 cat Results - Canine - Time elapsed before return of initial clinical signs 1-2 hours - 9 dogs 1-3 days - 32 dogs 7-9 days - 3 dogs 14 days - 1 dog 6 dogs never fed previous diet Results - Feline - Time elapsed before return of initial clinical signs 15-30 minutes - 2 cats 24 hours - 2 cats 2-3 days - 4 cats 6-8 days - 4 cats 10 days - 1 cat Age At Onset of Clinical Signs - Canine Range of 4 months to 11 years <1 year old - 17 dogs (33%) 1-3 years old - 26 dogs (51%) 4-11 years old - 8 dogs (16%) Age At Onset of Clinical Signs - Feline Range of 3 months to 11 years <1 year old - 3 cats (23%) 1-2 years old - 3 cats (23%) 4 years old - 2 cats (15%) 6-11 years old - 5 cats (39%) Breeds Affected - Canine Soft-Coated Wheaton Terrier, Dalmatian, Collie, West Highland White Terrier, Chinese Shar Pei, Lhasa Apso, Miniature Schnauzer, Cocker and Springer Spaniels, Labrador Retriever, Golden Retriever, German Shepherd, Bichon Frise Breeds Affected - Feline Siamese, Domestic Shorthair, Domestic Longhair Clinical Signs - Canine Non-seasonal pruritus Most commonly affects the ears/pinnae, feet, inguinal region, axillary region, proximal foreleg, face, neck, perianal/perineal region Chronic, recurrent otitis externa a common problem (Serous Otitis Media observed in 81/104 children from 1-9 years of age related to food allergy in 1 study) May develop secondary staphylococcal pyoderma or Malassezia dermatitis Possible history of seizures (Food Allergy and seizures in humans: seafoods and soybeans - increased dopamine in CNS) Concurrent diarrhea rare, may have more frequent or softer feces Only clinical sign on presentation: Chronic recurrent pyoderma Seborrheic dermatitis Clinical Signs - Feline Non-seasonal pruritus Most commonly affects the ear/pinnae, pre-aural region, neck, periorbital region and face Miliary type lesions most common ("Miliary dermatitis") Eosinophilic plaques Feline symmetrical alopecia Severe excoriations can occur Angioedema, urticaria, conjunctivitis Response to Glucocorticoids Complete cessation of pruritus Dogs - 39% of cases Cats - 64% of cases Partial reduction in pruritus Dogs - 44% of cases Cats - 9% of cases No reduction in pruritus Dogs - 17% of cases Cats - 27% of cases Concurrent Primary Pruritic Skin Diseases Flea Allergy Dermatitis Atopic Dermatitis Flea Allergy and Atopic Dermatitis Flea Collar Hypersensitivity DIAGNOSIS Treat suspected food allergy cases symptomatically for first 6-12 months before recommending an elimination diet trial Rationale For Initial Symptomatic Therapy For 6-12 Months 51 food allergic dogs followed for 3 years Only 3 dogs re-developed pruritus 2 dogs became flea allergic 1 dog became atopic None of the dogs became pruritic due to the new hypoallergenic treatment diet All dogs had been eating the initial sensitizing diet for 6-12 months or longer Dogs Started On Elimination Diet Prior To 6-12 Months Of Pruritus 2 cases initially on beef/soy based diets Placed on lamb based diets after 3 months Pruritus controlled for 2 months Pruritus re-developed and dogs found to be reacting to lamb Dogs Started On Elimination Diet Prior To 6 Months Of Pruritus 1 case initially on lamb/rice based diet Placed on venison based diet after 2 months Pruritus controlled for 3 months Pruritus re-developed and dog found to be reacting to venison Theory Of An Immunologic Window Patient is genetically programmed to become sensitized to commonly exposed antigens in the diet after a certain age At this age, sensitization begins over a 6-12 month time period? After this time period of programming, the sensitizing immunologic window closes Immunology of Food Allergy IgE mediated food allergy: Common in children - peaks at 1 yr. Consider skin testing and in-vitro serum testing in puppies? Rare in adults False negative skin tests in adults Delayed hypersensitivity reactions to foods: More common in adults Consider patch testing with foods ELIMINATION DIET TRIAL - MINIMUM 12 weeks in duration Protein hydrolysate formulated diets: Reducing the Molecular Weight (Daltons) of a specific protein in the diet DVM Pharmaceuticals - Exclude - Hydrolyzed casein and chicken liver, oat groats, pinto beans Purina CNM Diet - HA-Formula - Hydrolyzed soy, corn starch, canola/coconut oil Purina Gentle Snackers - Hydrolyzed soy, corn starch, canola/coconut oil, oat fiber Hill's Prescription Diets Canine z/d Ultra - Hydrolyzed chicken and chicken liver, corn starch, soybean oil Canine and Feline z/d Low Allergen - Hydrolyzed chicken and chicken liver, potato (canine), rice (feline), soybean oil Canine and Feline Hypoallergenic Treats - Hydrolyzed chicken and chicken liver, corn starch (dogs), rice (feline) soybean oil Royal Canin Veterinary Diet (Waltham) Hypoallergenic HP19 Canine - Hydrolyzed soy, rice, chicken fat, beet pulp, vegetable oil Hypoallergenic HP23 Feline - Hydrolyzed soy, rice, chicken fat, beet pulp, fish oil Home-cooked Elimination Diet Trial Restricted diet fed for up to 90 days Formulate based on known past exposure Avoid any previously consumed foods Canine Diets Protein sources Lamb, venison, rabbit, duck, goose, goat, ostrich, emu, alligator, kangaroo, elk, moose Cook by boiling, baking or broiling Carbohydrate sources Rice, potatoes, rutabagas - boiled, No instant or minute forms Sweet potatoes - baked Add nothing to the cooking water Mix equal portions of protein and carbohydrate (50:50) to approximate the volume of the previous diet 1 cup of the cooked mixture per 10 pounds of body weight per day Will need to increase the amount of carbohydrate 2-4 x for most dogs Use carbohydrate and/or protein treat between meals "Nothing else is to pass the dog's or cat's lips for the next 60 days" Discontinue all: Table scraps Dog and cat treats Chewable heartworm preventative Chewable vitamin supplements Essential fatty acid diet supplements Feline Diets Protein sources Rabbit, lamb, venison, duck Cook by boiling or broiling Carbohydrate sources Green peas Often refuse rice or potatoes Most often feed protein source alone Treatment Diets - Canine Lamb, venison or vegetable and rice based dry diets (Nature's Recipe) Rabbit and rice based canned diet (Nature's Recipe) Duck, venison, or salmon and potato based dry or canned diets; lamb and rice based canned diet, egg and rice based dry diet (d/d, Hill's) Venison, duck, rabbit, or whitefish and potato based canned and dry diets (Innovative Veterinary Diets - Royal Canin - Waltham) Vegetable and potato/oat/rice based dry diet (IVD Select Care Vegetarian Formula) Vegetable and rice/oatmeal/barley/potato based dry diet (Natural Balance Vegetarian Formula) Fish and potato based dry diet (Eukanuba Response Formula FP for Dogs) Salmon, trout and rice dry diet (Purina CNM Diet: LA-Formula); Menhaden fish meal and rice dry diet (Royal Canin - Skin Support SS21) Kangaroo and oat based dry diet (Eukanuba Response Formula KO for Dogs) Fish and sweet potato based dry diets Wellness Fish and Sweet Potato diet - whitefish, barley, rye flour, menhaden fish meal, canola oil California Natural Herring & Sweet Potato diet - herring, barley, oatmeal, herring oil, sunflower oil Natural Balance Sweet Potato and Fish diet - salmon, menhaden fish meal, canola oil Flint River Ranch "Fish and Chips" Trout and Sweet Potato diet - trout, millet, herring meal, oatmeal, canola oil Duck and sweet potato based dry diet - Fromm Duck and Sweet Potato Formula - barley, rice, oatmeal, egg, millet, tomato pomace, canola oil, cheese, carrots, broccoli, cauliflower, apples, green beans, cranberries, blueberries, chicory root, alfalfa sprouts, garlic, parsley Venison based dog treats - Nature's Recipe Healthy Skin Venison Dog Treat - soy flour, molasses, garlic powder; Shaffer Venison Farms - Venison Dog Treats - 100% smoked venison Sweet potato based dog treats - Sam's Yams Sweet Potato dog Chewz - 100% dried sweet potatoes/yams Treatment Diets - Feline Rabbit and rice based canned diets (Nature's Recipe) Venison, duck, or rabbit and green pea based dry or canned diets (d/d, Hill's) Lamb and barley based canned diet (Eukanuba Response Formula LB for Cats) Venison, lamb, duck, or rabbit and green pea based canned and dry diets (Innovative Veterinary Diet - Royal Canin - Waltham) Home Cooked Treatment Diets Protein source Lamb, venison, rabbit, chicken, turkey, beef, duck, ostrich Carbohydrate source Rice, potato, sweet potatoes, or rutabagas Essential fatty acid dietary supplement Derm Caps, EFA-Caps Dicalcium phosphate Non-flavored, additive free multiple vitamin and mineral supplement Taurine for cats EXclude DIET TRIALS Introduction Diagnosis of Food Allergy in Dogs Increasingly More Difficult Exposure to a wide variety of common and novel proteins and carbohydrates Finding a novel food source an extreme challenge Study Purpose "To evaluate the effectiveness of a novel carbohydrate and hydrolyzed protein diet in controlling pruritus in previously confirmed food allergic dogs". Patient Selection History of persistent, non-seasonal pruritus Dogs initially exposed to numerous common and novel proteins and carbohydrates Occurred prior to initiation of the home-cooked elimination diet trial Initial home-cooked diets fed (19 dogs): Venison and white potatoes (8 dogs) Venison and sweet potatoes (4 dogs) Duck and sweet potatoes (3 dogs) Duck and white potatoes (1 dog) Lamb and sweet potatoes (1 dog) Rabbit and sweet potatoes (1 dog) Pinto beans and white potatoes (1 dog) Initially fed the home-cooked diet for up to 8 weeks Then re-fed the previous diet for up 14 days until pruritus recurred Again fed the initial home-cooked diet until pruritus resolved Patient Selection - 19 dogs All dogs on treatment diets for >6 months prior to entering study: IVD - Venison/potato (8 dogs) IVD - Duck/potato (4 dogs) IVD - Lamb/potato (1 dog) IVD - Rabbit/potato (1 dog) Balanced home-cooked diets (5 dogs) Study Design Dogs initially examined and found to be free of any clinical signs or history of pruritus All dogs fed the novel carbohydrate (pinto beans, oats) and hydrolyzed protein (casein = 99.7% < 1100 Daltons, chicken liver = 99.8% < 1400 Daltons) diet (EXcludeR) for 30 days Owner to monitor each of the following: Palatability Gastrointestinal signs Weight Dermatologic signs and pruritus RESULTS All dogs re-examined in 30 days: Palatability Readily consumed (18 dogs); Refused diet after 9 days (1 dog) Gastrointestinal signs Diarrhea/soft feces (7 dogs) Weight - diet fed at a rate of 1/2 cup per 20# body weight Weight loss (11 dogs) Corrected by increased volume of food for each feeding except 1 dog Weight gain (0 dogs) Maintained weight (8 dogs) Dermatologic Signs and Pruritus Pruritus well controlled (18 dogs) Re-developed pruritus (1 dog) Occurred within 7 days of feeding Original treatment diet - Balanced home-cooked pinto beans and potatoes Conclusions EXcludeR adequate for controlling pruritus in a sizable number of known food allergic dogs May be a suitable substitute for a home-cooked elimination diet Problems encountered are similar to those when feeding a home-cooked elimination diet Treatment of Diarrhea/Soft Feces Submit fecal sample ASAP for direct exam Diff-Quik stain - Clostridial overgrowth Change to a home-cooked bland diet - Usually chicken and rice or potatoes Plain cultured yogurt added to diet Pepto-Bismol tablets - adult dosage Metronidazole (Flagyl) - 10 mg/kg BID x 7 days Foods Associated With Exacerbation of Clinical Signs Any food items being prepared in the kitchen Meats, cheeses, cooking oils, margarine, breads, odors from various cooked foods Peoples favorite snack foods Popcorn, pretzels, peanuts, cookies (Oreo), potato chips, corn chips, doughnuts, pizza, french fries "The Hoover Hound" New Dilemma Many patients with a possible food allergy that have already eaten and been exposed to "everything but the kitchen sink" Possible cross contamination of commercial diets during processing Prescription and non-prescription hypoallergenic diets Patients reacting to various ingredients used in the processing of commercial diets Treatment of Food Allergy Breast feeding exclusively for > 6 mos Decreased food allergy, atopic dermatitis, allergic rhinitis Oral cromolyn sodium (Gastrocrom) Increased G.I. permeability Enzyme potentiated desensitization Beta-glucuronidase + food Ag intradermally Enzyme treated foods - rice Gut sterilization treatment protocols Clostridium sp., Helicobacter sp. Decreases bowel inflammation and thereby decreases GI absorption of dietary allergens "Triple Therapy Regimen" - Canine Metronidazole - 15 mg/kg BID x 28 days Amoxicillin - 20 mg/kg TID x 28 days Bismuth subsalicylate (Procter) - 1 ml/kg QID x 28 days Food Allergy Potpourri Food challenge can be dose dependent Negative at small doses, positive after a large meal Children with egg allergy can react to mother's breast milk after eating eggs Cat with penicillin allergy can react to cow's milk containing penicillin Unique Food Related Reactions Onion powder in baby food Heinz body anemia in cats Allergenic food additives - Tartrazine (azo dyes), Na benzoate (preservative), MSG (flavor), Na bisulfate (anti-oxidant) Cutaneous vasculitis - Potatoes, green beans, peas, eggs Lupoid onychodystrophy, paronychia Reactive cutaneous histiocytosis Sterile granuloma/pyogranuloma Footpad hyperkeratosis with eosinophils Nasodigital hyperkeratosis Pinnal vasculitis, urticarial vasculitis Sebaceous adenitis Obsessive/compulsive disorders - Separation anxiety, Kleenex shredders, Lick granulomas Lethargy, depression, aggressive behavior Unique Reactions to Foods Food allergy to fish Exacerbated by inhalation of fish odors/fumes Food allergens in house dust Egg, milk, sugars Cross Reactions With Foods Pork-cat syndrome IgE reactions to pork meat and cat dander Bird-egg syndrome Bird feather allergy (asthma), followed by food allergy to eggs IgE mediated oral allergy syndrome Cross reactivity between pollens (birch, grass, mugwort) and foods (fruits, vegetables, nuts) Feline Eosinophilic Granuloma Complex "Eosinophilic Granuloma Confusion" Introduction Three reactions: Eosinophilic Ulcer, Eosinophilic Plaque, and Linear Granulomas (may occur in various combinations) This also represents a symptom response in cats and is NOT a specific disease entity. Many etiologies believed to be contributory: FeLV, FIV, FIP, allergy (atopic dermatitis, food allergy, flea allergy dermatitis), insect bite hypersensitivity (mosquitoes), bacteria, genetic predisposition. Eosinophilic Ulcer (Indolent Ulcer, Rodent Ulcer, Lip Ulcer) Etiology Symptom of an underlying allergic disease food allergy, atopic dermatitis, flea allergy dermatitis Occasionally responsive to systemic antibiotics or alpha interferon (latent viral infection, herpes or calici virus). Chronic forms of this reaction have been observed in FIP and FeLV positive cats. Clinical features Reddish brown erosion or ulcer, slightly raised, with a well-demarcated border. Usually unilateral on upper lip (may be multiple and affect upper and lower lips, nose, periorbital area, and oral mucosa or any combination). Non painful and non pruritic. Can be severely erosive lesions. Hemogram normal. Watch progression; may change to squamous cell carcinoma or a plasma cell ulcerative dermatitis. Diagnosis History and physical exam. Histopathology: true ulcer, and perivascular infiltration of neutrophils, lymphocytes, plasma cells and fibroblasts. Very nonspecific. In-vitro serum testing (ELISA tests) for allergen-specific IgE to aeroallergens and insects (not Intradermal testing), hypoallergenic diet trials, response to antibiotics. FeLV tests, FIP titer, PCR for herpes, calici virus isolation. Pedigree review. Macerated tissue culture. True ulcer, not associated with blood eosinophilia and not a granuloma. Treatment - Identify and treat any underlying problem Herpes or Calici Viral associated Pure lysine granules (78.8% lysine) ¼ teaspoon (~570 mg) q12h for life L-lysine tablets (no propylene glycol!) 250-500 mg/cat for life L-lysine gel or powder (VIRALYS™) 250 mg/cat for life Imiquimod (Aldara®) 5% cream - 3 times weekly Alpha interferon - 30-1000 units orally SID Underlying Allergic Diseases Flea treatment protocol Allergen-specific immunotherapy (ASIT) Hypoallergenic treatment diets Systemic antibiotics Cephadroxil 22 mg/kg BID x 30 days, Trimethoprim/Sulfadiazine 30 mg/kg BID x 30 days, Amoxicillin/Clavulanic Acid - 12.5 mg/kg BID x 30 days Corticosteroids Methylprednisolone acetate (DepoMedrol®): 10 15 mg/cat IM or SQ Prednisolone 0.5 mg/lb BID to induce remission; decrease to lowest alternate day dose (or eliminate, if possible) Progesterones only if the above treatments have failed Megestrol acetate (Ovaban®): 2.5 5 mg/cat q 48 h to induce remission, then reduce to every 3 7 days to maintain Repositol progesterone 1 10 mg/lb IM or SQ; lasts 4 6 weeks Medroxyprogesterone acetate 50 175 mg/cat; lasts 4 6 weeks Omega 3 and 6 fatty acids As last resort, try 0.5 cc triamcinolone/lesion (Vetalog®), 6 mg/ml concentration, intralesionally Eosinophilic Plaque Etiology see eosinophilic ulcer (esp. Flea allergy, food allergy, and atopic dermatitis) Clinical features Raised, well circumscribed, plaque like lesions which are frequently moist and erythematous Found most commonly on abdomen and medial thighs Single or multiple; often symmetrical Associated with excessive licking; controversy exists as to which came first Diagnosis History and physical examination Histopathology: spongiosis, epidermal hyperplasia, intraepidermal microvesicles with eosinophils and perivascular or diffuse dermal infiltration of eosinophils and mast cells. Hemogram commonly shows eosinophilia. In-vitro serum testing (ELISA tests) for allergen-specific IgE to aeroallergens and insects (not Intradermal testing), hypoallergenic diet trials, response to antibiotics FeLV and FIV tests, FIP titer True plaque: associated with tissue and blood eosinophilia; not a true granuloma. Treatment see eosinophilic ulcer. Collagenolytic Granuloma - now called "Feline Eosinophilic Dermatoses (Linear Granuloma, Eosinophilic Granuloma) Etiology see eosinophilic ulcer Has been associated with an insect bite hypersensitivity reaction (mosquitoes) on a seasonal basis Food allergy associated Cutaneous and oral forms Cutaneous forms Linear, sharply demarcated, raised, firm, yellowish pink lesion on caudal or medial aspect of rear legs Swollen chin form Dorsal planum of nose and ear reaction to insect bites Non pruritic and non painful. Oral form Raised, firm, yellowish pink focal nodule, plaque or cauliflower like lesion (not linear) Usually seen on lower lip, tongue, gingiva and palate. Asymptomatic in that there is no licking, pain or excess salivation Diagnosis History and physical examination Histopathology: nodular to diffuse granulomatous inflammation with degeneration of collagen (collagenolysis, flame figures) In-vitro serum testing (ELISA tests) for allergen-specific IgE to aeroallergens and insects (not Intradermal testing), hypoallergenic diet trials, response to antibiotics FeLV tests, FIP titers Treatment see eosinophilic ulcer Diagnosis and Management of Cutaneous Drug Reactions in Dogs and Cats PATHOGENESIS: Immunologic Type I, II, III, IV hypersensitivity reactions Nonimmunologic Related to pharmacology of the drug Predictable, dose dependent Route of administration Oral Topical Injectable Inhalation Clinical Presentations: Erythema multiforme Toxic epidermal necrolysis Pemphigus foliaceus Vaccine reaction Cutaneous vasculitis Lichenoid Drug Eruption Unique Feline Reactions: Miliary dermatitis reaction Vaccine reaction Injection site fibrosarcomas ERYTHEMA MULTIFORME Drug-induced apoptosis Programmed cell death Acute onset of lesions Erythematous macules "Target lesions" Urticarial plaques Vesicles and bullae Concurrent systemic illness Fever, depression, anorexia Mucous membrane involvement Vesicles, bullae, ulcers Erythema multiforme major or Stevens-Johnson syndrome Can be life threatening Drugs implicated Aurothioglucose Cephalexin, chloramphenicol, gentamicin, trimethoprim sulfas, ormetoprim sulfas, tetracycline Diethylcarbamazine, levamisole L- thyroxine, phenobarbitol TOXIC EPIDERMAL NECROLYSIS Severe erythema multiforme? Massive and sudden apoptosis Diffuse erythematous rash Vesicles and bullae Full thickness skin sloughing and ulcers May affect footpads, mucous membranes Lesions usually painful Concurrent fever, anorexia, lethargy, depression Secondary sepsis a problem Often a fatal disease Drugs implicated Penicillins, cephalosporins, trimethoprim sulfas Griseofulvin Levamisole 5- fluorocytosine Topical flea dips (D-limonene) DRUG-INDUCED PEMPHIGUS Mimics Pemphigus foliaceus Acute, transient pustular eruptions Subsequent crusts, scales, erosions, epidermal collarettes Variable distribution patterns Systemic illness rare Drugs implicated Ampicillin, cephalosporins, sulfonamides Diethylcarbamazine, thiabendazole Cimetidine, procainamide VACCINE REACTIONS Most commonly observed at site of a subQ or IM vaccination Rabies, DHLP- Parvo Can occur from weeks to months post-vaccination Focal area of alopecia and hyperpigmentation Breed predisposition Poodle, Bichon Frise Shih Tzu, Lhasa Apso Miniature Schnauzer, Yorkshire Terrier, Bedlington Terrier, Silky Terrier Most spontaneously resolve over several months Lesion may remain static Area of alopecia and hyperpigmentation can gradually enlarge over months to years Treatment Tincture of time Surgical excision Pentoxifylline (Trental) 15 mg/kg TID x 3 months CUTANEOUS VASCULITIS Palpable purpura, hemorrhagic bullae Craterform ulcers, full thickness skin sloughing Acrocyanosis of distal extremities Large areas of erythematous or purplish skin Does not blanch on dioscopy Lesion often painful Pitting edema of distal extremities Concurrent systemic illness Anorexia, depression, fever Drugs implicated Penicillins, sulfonamides, cephalosporins, dexamethasone DHLP- Parvo vaccine LICHENOID DRUG ERUPTION Solitary to multiple papillomatous or plaque-like lesions Drugs implicated Cyclosporine (Atopica, Neoral, Gengraf) MILIARY DERMATITIS REACTION Miliary lesions Affects head, face, neck regions Intense pruritus Mimics "food allergy" Drugs implicated Methimazole (Tapazol), Propranolol VACCINE REACTION Injection site fibrosarcomas Interscapular and femoral regions Associated with either subQ or IM injections Tumor may develop 1-2 years post -vaccination Vaccines implicated: FeLV, Rabies, FVRCP DIAGNOSIS OF CUTANEOUS DRUG REACTIONS History Observed reaction does not resemble pharmacologic action Prior exposure to drug may have been well tolerated Reaction can be reproduced by small amounts of drug Reaction consistent with a known hypersensitivity response Reaction occurs within several days of drug exposure Resolution within several days of drug withdrawal Drug rechallenge Proves cause and effect relationship Clinical signs often more severe Outcome can be fatal Erythema Multiforme Histopathology Hydropic interface dermatitis Dyskeratotic keratinocytes with satellitosis Superficial perivascular infiltrates with mononuclear cells Toxic Epidermal Necrolysis Histopathology Hydropic degeneration of basal cells Coagulation necrosis of epidermis Absence of dermal inflammation Dermoepidermal separation and bullae formation CLINICAL CRITERIA EMm EMM SJS OVE TEN Flat or raised, focal or multifocal, target lesions Yes Yes No No No Number of mucosa involved <1 >1 >1 >1 >1 Erythematous or purpuric, macular or patchy eruption <50% <50% >50% >50% >50% Epidermal detachment <10% <10% <10% 10-30 >30% Olivry T et al: Erythema multiforme, Stevens-Johnson syndrome, and toxic epidermal necrolysis in the dog: Clinical classification, drug exposure, and histopathological correlations. Proceedings of the Autumn Meeting of the British Veterinary Dermatology Study Group, 1998, York, United Kingdom. Pemphigus Foliaceus Histopathology Subcorneal pustules Acantholytic cells Neutrophils, eosinophils Involvement of hair follicles Vaccine Reaction Histopathology Vasculitis, panniculitis Dermal edema Atrophic hair follicles Hydropic degeneration of basal cells Cutaneous Vasculitis Histopathology Most commonly leukocytoclastic Neutrophils in vessel walls "Nuclear dust" Fibrinoid degeneration, thrombi Perivascular hemorrhage and edema LICHENOID DRUG ERUPTION Histopathology Psoriasiform lichenoid dermatosis - with or without papillomavirus UNIQUE FELINE REACTIONS: Miliary dermatitis Histopathology Epidermal crusts, spongiosis Neutrophilic, eosinophilic vesicopustules Eosinophilic perivascular infiltrates Vaccine Reactions Histopathology Fibrosarcoma TREATMENT Discontinue suspected drug Avoid chemically related or similar drugs When multiple drugs are present: all should be discontinued Best advice: "Do no harm!" For Idiopathic cases (Erythema multiforme, cutaneous vasculitis, miliary dermatitis) - consider hydrolysate treated or home-cooked elimination diet trial Supportive Therapy - IV Fluids Systemic antibiotics in septic patients Broad spectrum initially Cephalexin - 10 mg/lb TID Based on culture and sensitivity Gram negative organisms Ciprofloxacin - 22 mg/kg SID Immunosuppressive Drugs Extremely controversial May actually be contraindicated Increased risk of infections, delayed healing Indicated in drug induced Erythema Multiforme major Corticosteroids: Prednisolone 1 mg/lb SID-BID Immune Modulating Drugs: Cyclophosphamide - 1 mg/lb SID Cyclosporine (Neoral, Gengraf, Atopica) - 5 mg/kg SID-BID Azathioprine (Imuran) - 1 mg/lb SID, Pentoxifylline (Trental) - 15 mg/kg TID Malassezia Dermatitis Etiology Malassezia pachydermatis Syn. - Pityrosporum canis Lipophilic, nonmycelial yeast Elongated oval shape, unipolar budding, thick cell wall Pathogenesis Part of normal flora of canine skin, and nasal and oral mucosa May involve a hypersensitivity reaction Type I hypersensitivity (immediate) Type IV hypersensitivity (delayed) Antigenic component may be: Cell wall associated Cytoplasmic constituent Secretory factor Probably not a primary disease process Seen in association with other primary skin diseases Atopic dermatitis Food allergy Seborrheic skin disease Scabies Previous exposure to systemic antibiotics Breed predisposition - Basset Hound, Dachshund, West Highland White Terrier, American Cocker Spaniel, Shih Tzu, English Setter Clinical Features Extremely variable - usu. pruritic May depend on type of primary skin disease present Lesions may include: Erythematous patches Moist, greasy, malodorous skin Hyperpigmented, lichenified skin Seborrheic plaques Areas Most Commonly Affected Ventral neck Interdigital region Proximal anterior foreleg Perioral region, chin Diagnosis Evaluate for primary problem History of increased pruritus Greasy, malodorous skin Poor response to systemic steroids and/or antibiotics Poor response to antibacterial and antiseborrheic shampoos Diagnosis Skin cytology examination Direct impression smear Dry swab sample Stained with Diff-Quik stain Yeast are difficult to find in normal dogs Examine under oil immersion (100 X) Skin biopsies for histopathologic examination Stained with Gram's stain Treatment Topical - bathe twice weekly for 4 weeks Miconazole shampoo (Dermazole, Miconazole) Miconazole conditioner (ResiZole leave-on conditioner) Chlorhexidine shampoo (ChlorhexiDerm Maximum 4%, Hexadene 3%, Douxo Chlorhexidine 3% PS) Selenium disulfide shampoo (Seleen) Ketoconazole shampoo (Nizoral) Enilconazole rinses (Imaverol) Miconazole cream (Conofite) Miconazole and Chlorhexidine (Malaseb shampoo, flush, pledgets) Ketoconazole and Chlorhexidine (KetoChlor shampoo) Systemic Ketoconazole (Nizoral) - 10 mg/kg SID, orally x 30 days Potential hepatotoxicity Expense Itraconazole (Sporanox) - 5/10 mg/kg SID, orally x 30 days Fluconazole - 5 mg/kg SID, orally x 30 days Seasonal Flank Alopecia Etiology Unknown Change in photoperiod important Role of pineal gland controlled hormones Prolactin Melatonin Localized hair follicle hormone receptor abnormality Sex Predisposition Most frequently reported in spayed females Can occur in intact males or females and neutered males Breed Predisposition Boxers Airedale Terriers Bulldogs Giant and Miniature Schnauzers Bouvier de Flanders Doberman Pinschers Scottish Terriers German Wirehaired Pointers Clinical Features Bilaterally symmetrical alopecia with hyperpigmentation Affects primarily the flank region May extend to the lateral thorax or dorsally Most commonly occurs in fall/early winter and resolves in late spring/early summer. Cyclical pattern may vary Diagnosis History and physical exam Rule out other endocrine skin diseases Hypothyroidism Cushing's Disease Reproductive hormone imbalances Histopathology Follicular atrophy, keratin plugging, comedone formation "Witches-foot" appearance Hypermelanosis Treatment None established at this time Manipulation of photoperiod Use of exogenous prolactin or melatonin Melatonin - 1-6 mg/dog TID for the duration of the Alopecic cycle. Needs to be started prior to the onset of alopecia. Lupoid Onychodystrophy Pathogenesis Unknown Suspected to be a lupus-like, immune-mediated disease Secondary bacterial paronychia common (esp. Staphylococcus intermedius) A possible "novel" reaction pattern to "common" underlying diseases Food Allergy Atopic Dermatitis Clinical Features German Shepherd dogs predisposed Acute onset of sloughing of one or more nails Nails avulse by lifting up distally from the corium, and continuing proximally to the claw fold Lameness associated with avulsion of each nail Subsequent loss of all nails may occur over several weeks to months Regrowth characterized by short, malformed, soft, dry, brittle nails Diagnosis Rule out potential underlying disease processes: CBC, Profile, U/A ANA, Cold Agglutinins Elimination diet trial testing Intradermal skin testing Macerated tissues culture of nail Bacterial culture and sensitivity Fungal culture Nail biopsy techniques: P3 amputation Longitudinal punch biopsy (8 mm) Nail trim flush to the nail fold Histopathology: Hydropic degeneration of basal cells Lichenoid interface dermatitis Treatment Treat underlying disease process if possible Hypoallergenic diets Aqueous hyposensitization Tetracycline and Niacinamide - 10 mg/lb of each TID Doxycycline - 5-10 mg/kg SID (with or without concurrent Niacinamide) Essential fatty acid supplements - Derm Caps SID Pentoxifylline - 15 mg/kg TID Vitamin E - 400-800 IU's - BID Cyclosporine - 5 mg/kg SID Systemic antibiotics based on culture and sensitivity for secondary paronychia Cephalexin - 15 mg/lb BID x 2-4 months Prognosis Discontinuation of therapy invariably results in relapses Regrown nails are usually malformed, soft, and friable Process of avulsing nails and lameness is halted Sebaceous Adenitis Etiology Unknown May be an immune mediated disease May be a genetically inherited defect - autosomal recessive trait. Keratinization abnormality with obstruction of sebaceous duct? Abnormality in sebaceous lipids? Clinical features 2 forms Sebaceous Adenitis with Hyperkeratosis - Long Coated Breeds Seen in all color variants of standard poodles (may be similar in other long coated breeds of dogs such as Samoyeds and Akitas). A symmetrical partial alopecia and excess scaling with follicular casts. Remaining hair is dull and brittle. Affects dorsal planum of the nose, top of head, dorsal neck and trunk, tail and pinnae. Non pruritic and no offensive odor May develop secondary bacterial folliculitis with pruritus. Hair may become straight and lose its "curl". Granulomatous Sebaceous Adenitis - Short Coated Breeds Affects short coated breeds of dogs Vizslas, Weimaraners Begins as a moth eaten alopecia with minimal to no scaling. Primarily affects the trunk, head and ears. Non pruritic Diagnosis Histopathology Initial nodular granulomatous to pyogranulomatous inflammation at the level of the sebaceous glands. Depending on the type, there may or may not be prominent hyperkeratosis. Chronic cases develop a complete loss of sebaceous glands with fibrosis, atrophy of hair follicles and in some cases complete loss of the adnexa with fibrosis. Treatment Propylene glycol a hygroscopic lipid solvent that penetrates the horny layer and increases water content. 50 75% propylene glycol with water applied daily as a spray. Bath Oil Treatments (light mineral oil) - 50:50 mixture of bath oil and water, spray over the entire body, rub into the hair coat well, allow to soak for 1-2 hours. Remove oil by bathing with dish soap 2-3 times, and then finish with a moisturizing shampoo and conditioner/crème rinse for the final bathing. Repeat q 7 days for the first month, the q 14-30 days prn. EFA Supplement - Derm Caps ES - 1 capsule BID; Evening Primrose Oil (EPO) - 500 mg BID. Anti seborrheic shampoos, conditioners and emollients have been of little benefit. Treat secondary pyoderma if present. Isotretinoin (Accutane®) - 1 mg/kg SID-BID. Acetretin (Soriatane®) - 1 mg/kg SID-BID Cyclosporine (Neoral, Gengraf, Atopica) - 5 mg/kg BID. Retinol (Vitamin A) - 8,000-20,000 IU - SID-BID Prognosis Akitas - tends to be more severe, chronic recurrent pyoderma more of a problem, possible signs of systemic illness. Standard Poodles - aesthetic disease, secondary pyoderma rare, difficult to regrow "normal" hair coat. Short Coated Breeds - occasionally "cured" by treatment.

© 2008 - Edmund J. Rosser Jr., DVM, Diplomate ACVD - All rights reserved