Diagnosis and treatment of food allergy in dogs (Proceedings)

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 and

• 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 - lamb, venison, moose, elk, rabbit, duck, goose, goat, ostrich, emu, alligator, kangaroo, pinto beans

• Carbohydrate source - rice, potatoes, sweet potatoes (yams), rutabagas, oats, barley

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

• Since the original study, dogs have now been observed to take as long as 90 days to respond to a home-cooked elimination diet trial.

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

“Why All The Fuss About Home-Cooked Elimination Diets?”

• White SD: Food hypersensitivity in 30 dogs. JAVMA, vol 188 (7):695-698, 1986.

• 7/13 dogs (54%) with confirmed food allergy on a home-cooked lamb and rice diet, relapsed when feed a commercial canned lamb and rice diet.

• Jeffers JG, Shanley KJ, Meyer EK: Diagnostic testing of dogs for food hypersensitivity. JAVMA, vol 198 (2):245-250, 1991.

• 2/13 dogs with confirmed food allergy on a home-cooked lamb and rice diet, relapsed when feed a commercial dry egg and rice diet = 15% error.

• Sensitivity of serum allergen-specific IgE testing to foods (ELISA) 13 dogs = 14%.

• Sensitivity of Intradermal Testing to foods in 13 dogs = 10%.

• Kunkle G, Horner S: Validity of skin testing for diagnosis of food allergy in dogs. JAVMA, vol 200 (5):677-680, 1992.

• Out 28 dogs with a positive skin test reaction to foods, only 3 dogs responded to a home-cooked lamb and rice diet.

• Rosser EJ: Diagnosis of food allergy in dogs. JAVMA, vol 203 (2):259-262, 1993.

• 51 food allergic dogs confirmed over a 2-year time while being fed a home-cooked elimination diet for 10 weeks. 3 week trial only adequate for 25% of dogs.

• Recent data: 25% of dogs on home-cooked elimination diets relapse when fed any form of commercial hypoallergenic dog food.

Serologic Test for Food-Specific IgE:

• Hillier A, Kunkle G: Inability to demonstrate food antigen-specific IgE antibodies in the serum of food allergic dogs using the PK and oral PK tests. 10th Proceedings of the ACVD Meeting, 1994.

• No + reactions in 10 know food allergic dogs.

• Mueller R, Toshalis J: Evaluation of serum allergen-specific IgE for the diagnosis of food adverse reactions in the dog. Vet Derm, 9:167-171, 1998.

• No + reactions in 8 known food allergic dogs.

Disclaimer on allergen-specific IgE testing for foods (HESKA):

• “Not all patients with adverse reactions to food have significant scores on serum IgE tests. The gold standard for determination of food allergies remains the compliant food trial. Diet selection should include patient diet history and should supply a restricted number of one or two novel protein sources to which the patient has not had prior exposure. Diet trials should run a minimum of 10-12 weeks.”

Disclaimer on allergen-specific IgE testing for foods (VARL-Liquid Gold):

• “Elimination diets lasting 6 to 12 weeks - the test method of choice.  Feed a single protein source and a single carbohydrate source that the patient has not eaten before.  Frustrating for clients and practitioners!  Skin testing for food allergy not reliable.”

Age At Onset of Clinical Signs - Canine

• Range of 4 months to 11 years – New record of age of onset of clinical signs related to a food allergy in dogs is 13 year of age!; <1 year old - 17 dogs (33%) – including puppies at 7 weeks of age!; 1-3 years old - 26 dogs (51%); 4-11 years old - 8 dogs (16%) - Compared to Atopic Dermatitis and Flea Allergy Dermatitis, this is older in general for the development of an allergic skin disease.

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

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)

• Infectious Otitis Media: Defalque VE, Rosser EJ, Petersen AD: Aerobic and anaerobic bacterial microflora of the middle ear cavity in normal dogs. 20th Proceedings of the ACVD Meeting, 2005.

•     Staphylococci, Streptococci, Enterococci, Bacilli, Bordatella bronchiseptica, NO YEAST.

• 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

Response to Glucocorticoids

• Complete cessation of pruritus - 39% of cases; Partial reduction in pruritus - 44% of cases; No reduction in pruritus -  17% 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 z/d Low Allergen - Hydrolyzed chicken and chicken liver, potato (canine), rice (feline), soybean oil

• Canine 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

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 scrapes; Dog treats; Chewable heartworm preventative - Flavorings in Chewable Heartworm Preventatives: Heartgard and Heartgard Plus - Real beef, corn, soy (Unflavored tablet available); Sentinel and Interceptor - Pork liver, soy; Iverhart Plus - Pork liver; Flavorings in Miscellaneous Chewable Products - Proin (phenylpropanolamine) - Poultry liver; Propalin (phenylpropanolamine) – Beef; Deramaxx (deracoxib) - Pork, soy; Baytril (enrofloxacin) - Pork liver, hydrolyzed soy; Rimadyl (carprofen) - Pork liver; Chewable vitamin supplements; Essential fatty acid diet supplements

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

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

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