Prospective clinical evaluation of food allergic 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

• Protein sources - rabbit, venison, lamb, duck, goose, ostrich, emu

• Carbohydrate source - green peas, rarely rice or potatoes

Results - Time elapsed before maximal clinical response

• 1-3 weeks - 4 cats

• 4-6 weeks - 7 cats

• 7 weeks - 1 cat

• 9 weeks - 1 cat

• Recent date – diet trials x 12 weeks

Results - 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

• Recent data – feed previous diet x 14 days

Age At Onset of Clinical Signs

• 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%)

• Compared to Atopic Dermatitis and Flea Allergy, this is older in general for the development of an allergic skin disease

• New Record = 12 years of age

Breeds Affected

• Siamese, Domestic Shorthair, Domestic Longhair

Clinical Signs

• 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, Rodent ulcers

• Feline symmetrical alopecia

• Severe excoriations can occur

• Angioedema, urticaria, conjunctivitis

Response to Glucocorticoids

• Complete cessation of pruritus - 64% of cases

• Partial reduction in pruritus - 9% of cases

• No reduction in pruritus - 27% of cases

Graham-Mize CA, Rosser EJ, Hauptman J: Absorption, bioavailability and activity of prednisone and prednisolone in cats. Adv Vet Derm, vol. 5: 152-158.

• Greater than a 6-fold difference in Cmax of oral prednisolone (Cmax= 1400 ng/ml) vs. oral prednisone (Cmax= 220 ng/ml)

• Cmax of oral prednisolone after oral prednisone only 122 ng/ml

• Results indicate both a decreased gastrointestinal absorption of prednisone compared to prednisolone, and possible decreased conversion of prednisone (inactive form) to prednisolone (active form) by the liver in cats = 12 fold difference

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 kittens?

• 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 8-12 weeks in duration

Protein hydrolysate formulated diets:

Reducing the Molecular Weight (Daltons) of a specific protein in the diet

• Purina Veterinary Diets - HA Formula - Hydrolyzed soy (10,000 Daltons), corn starch, canola/coconut oil – Experimental Trial Diet Only

• Hill's Prescription Diets

• Feline z/d Ultra (canned) - Hydrolyzed chicken liver (3,000 Daltons), corn starch, soybean oil

• Feline z/d Low Allergen(dry) - Hydrolyzed chicken liver, rice, soybean oil

• Feline Hypoallergenic Treats - Hydrolyzed chicken liver, rice,  soybean oil

• Royal Canin Veterinary Diet (Waltham)

• Hypoallergenic HP23 Feline – Hydrolyzed soy (10,000 Daltons), rice, chicken fat, beet pulp, anchovy oil, soya 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

• “Nothing else is to pass the cat's lips for the next 60 days”

Discontinue all

• Table scrapes

• 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 - feline

• Rabbit and rice based canned diets (Nature's Recipe)

• Venison, duck, or rabbit and green pea based canned and dry diets (d/d canned, Hill's)

• Lamb and barley based canned diet (Eukanuba Response Formula LB for Cats)

• Lamb, venison, duck, or rabbit and green pea based canned and dry diets (Royal Canin/Waltham/Innovative Veterinary Diets)

Home cooked treatment diets

Protein source

• Lamb, venison, rabbit, chicken, turkey, beef, duck, goose, ostrich, emu

Carbohydrate source

• Green pea, rice, potato or sweet potatoes

Essential fatty acid dietary supplement

• Derm Caps, EFA-Caps

Dicalcium phosphate

• Non-flavored, additive free multiple vitamin and mineral supplement

• Taurine for cats

Balanced home-made elimination diet for cats

• ½ pound cooked potatoes, rice, or green peas

• 1 pound cooked lamb, venison, ostrich, emu, rabbit, or duck

• 1 teaspoon Dicalcium phosphate

• ½ tablespoon Safflower Oil (Hollywood Brand only)

• 2 teaspoons light salt

• 1½ tablets of Nature Made® Multi Max – Complete Multi Vitamin/Mineral Supplement with Iron

• 350 mg Taurine

Feeding guidelines:

• Broil, boil, or bake lamb and grind or finely chop.

• Add salt to cooking water for rice, potatoes, or green peas. Mix the safflower oil, Dicalcium phosphate, vitamin/mineral supplement, and taurine with the rice, potatoes, or green peas, and then add the mixture to the meat puree. Keep refrigerated and warm in microwave to increase palatability.

• Feed 2½ ounces/5 pounds of cat/day.

Foods associated with exacerbation of clinical signs

• Any food items being prepared in the kitchen - “The Counter Cat”

• 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

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