Small animal food and environmental allergies
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Small Animal Food and Environmental Allergies . Heather Haskins Emily Mercer. Contents. Atopic Dermatitis Allergic Contact/Inhalant Dermatitis Food Allergy Dermatitis. Atopic Dermatitis. Inherited type I hypersensitivity reaction to environmental allergens.

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Small Animal Food and Environmental Allergies

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Small Animal Food and Environmental Allergies

Heather Haskins

Emily Mercer


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Contents

  • Atopic Dermatitis

  • Allergic Contact/Inhalant Dermatitis

  • Food Allergy Dermatitis


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Atopic Dermatitis

  • Inherited type I hypersensitivity reaction to environmental allergens


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What is a type I hypersensitivity reaction?

  • Allergen contact induces allergen-specific IgE antibody production leading to memory cell hyper reactivity upon reexposure


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Normal Immune Response


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Type I hypersensitivity rxn


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Breeds most commonly affected by Atopic Dermatitis

  • West Highland white terriers

  • Wire-haired fox terrier

  • Cairn terrier

  • Scottish terrier

  • English setter

  • Miniature schnauzer

  • Lhasa apso

  • Chinese shar-pei


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Clinical Signs of Atopic Dermatitis

  • Pruritis

  • Self-inflicted excoriations

  • Salivary staining

  • Alopecia

  • Lichenification

  • Hyperpigmentation

  • Otitis externa


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Clinical signs of Atopic Dermatitis

  • Erythema

  • Secondary Infections:

  • Malassezia dermatitis

  • Serous pyoderma

  • Hemorrhagic pyoderma


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Allergic Contact Dermatitis

  • Type IV hypersensitivity reaction to environmental allergens by direct contact


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What is a type IV hypersensitivity reaction?

  • Delayed hypersensitivity reaction mediated by lymphocytes, a cell-mediated reaction


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Common Contact Allergens

  • Insecticides in flea collars, sprays, dips

  • Wood preservatives

  • Floor waxes

  • Carpet dyes

  • Some pollens

  • Dermatological drugs

  • Leather products

  • Paints

  • House plants


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Clinical Signs of Contact Dermatitis, Acute Lesions

  • Affects relatively hairless portions of body

  • Erythema

  • Papules

  • Vesicles which rupture to form crusts


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Clinical Signs of Contact Dermatitis, Chronic Lesions

  • Alopecia

  • Hyperpigmentation

  • Lichenification

  • Self-inflicted trauma


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Atopic Dermatitis

  • Type I hypersensitivity

  • Hyperemia,pruritis

  • Face,nose,eyes,feet, perineum

  • Foods,pollens,fleas, inhaled allergens

  • Intradermal testing, immediate response

  • Eosinophilic filtration, edema

  • Steroids, antihistamines, hyposensitization

Contact Dermatitis

  • Type IV hypersensitivity

  • Hyperemia, vesiculation,alopecia,erythema,

  • Hairless areas

  • Reactive chemicals

  • Delayed response on patch testing

  • Mononuclear cell infiltration, vesiculation

  • Steroids


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Diagnosing Atopic and Allergic Contact Dermatitis

  • Take skin scraping and perform fecal float

  • IDAT: Intradermal allergy testing

  • In vitro testing: ELISA, RSAT


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IDAT Requirements

  • Animal’s allergy season lasts longer than 3 months

  • Medical therapy no longer controls the symptoms

  • Avoidance of allergens is not possible

  • Animal is young and would benefit from long-term immunotherapy


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IDAT Test

  • As a pretest, inject .1ml of 1:100,000 histamine phosphate as the positive control and .1ml of saline as the negative control before performing the full skin test

  • Read the test 10-15 minutes after making the injections

  • A red, firm wheal ~15mm in diameter or 4X the size of saline control bleb is adequate positive response to histamine


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Skin Testing


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In Vitro Tests:ELISA,RSAT

  • Useful when IDAT not an option

  • Commercially available

  • Sedation is not required

  • Antihistamines and NSAIDS need not be discontinued

  • Lesser amounts of serum needed

  • Lower specificity


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Treatments

  • Hyposensitivity immunotherapy vaccines

  • Corticosteroids

  • Topicals

  • Antihistamines

  • Essential Fatty Acids

  • NSAIDS


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Immunotherapy with Hyposensitization

  • Allergy vaccines are made for individual patients based on either serologic or IDAT results

  • Goal of therapy: to increase the patient’s ability to tolerate environmental allergens without clinical signs


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Statistics Associated with Immunotherapy

  • ~25% improve in 3 months

  • Another 50% in 6 months

  • Remaining 25% in 6-12 months


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Food Allergy Hypersensitivity

  • Suspect if: non seasonal pruritic lesions, no response to steroids or NSAIDS (dogs), no response to progestational drugs (cats)

  • Immediate (type 1) and delayed (type 4) food reactions


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Breeds Most Susceptible to Food Allergy Dermatitis

  • Miniature schnauzer

  • Golden retriever

  • West Highland white terrier

  • Chinese shar-pei


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Clinical Signs of Food Allergy Dermatitis

  • Non seasonal pruritis

  • Ear canal disease that manifests as pruritis and secondary bacterial and yeast infections

  • Blepharitis

  • Generalized seborrhea

  • Papular eruption


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Patient with Food Allergy Dermatitis


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Diagnosing Food Allergy Dermatitis

  • Only reliable diagnostic test= food elimination diet

  • Trial diet fed up to 3 months

  • To confirm that food allergy exists, the patient should be rechallenged with previous food and a relapse of clinical signs must occur


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Most Frequent Food Allergens (Dogs)

  • Beef

  • Chicken

  • Corn

  • Wheat

  • Soy

  • milk


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Most Frequent Food Allergens (Cats)

  • Fish

  • Chicken

  • beef


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Hypoallergenic Test Diet

  • Feed limited number of food-stuffs

  • Dogs: 1:1 mix of pinto beans and potatoes

  • Cats: lamb based baby food, without onion

  • Prescription diet

  • Do not give palatable meds such as heart worm preventatives, vitamins


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Food Allergy Treatments

  • Home made diets consisting of balance of protein, carbohydrate, vitamins, minerals, and taurine for cats

  • Commercially available limited-allergen diets


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Two cases: Theodore and Toby

  • Theodore “Teddy”

  • 11 years old

  • Neutered male

  • Lhasa apso


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Teddy’s history of skin problems

  • Scabies

  • Fleas

  • Year round pruritus


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Teddy’s Therapy

  • Weekly baths

  • Steroid therapy during intense flare-ups


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Toby’s problems

  • Toby: 1 ½ years, neutered male, black lab/basset hound mix

  • Chronic yeast infection – otitis externa


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Toby’s Food Allergy

  • Hill’s Z/D food elimination diet for 6 months

  • Hill’s D/D duck and rice diet fed daily

  • No other treats

  • Ice cubes


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Food Elimination Diet

  • Hill’s Z/D Ultra Low Allergen food

  • Side effects

  • Fed for specified period of time


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Conclusions

  • Trial and Error

  • Individuality of each patient


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References:

  • The Merck Veterinary Manual 8th edition, Aiello, Mays 1998 Merck & Co. INC.

  • Veterinary Pathology 6th edition, Jones, Hunt, King 1997 Williams & Wilkins

  • Saunders Manual of Small Animal Practice 2nd edition, Birchard and Sherding 2000 W.B Saunders Company

  • Veterinary Immunology 6th edition, Tizard, W.B Saunders Co. 2000


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