UNIVERSITY OF CALIFORNIA, DAVIS
VETERINARY MEDICAL TEACHING HOSPITAL
SCHOOL OF VETERINARY MEDICINE
DAVIS, CA 95616
SMALL ANIMAL CLINIC 530-752-1393
DERMATOLOGY SERVICE
Information for Clients
Food Allergy Dermatitis
Introduction
Food Allergy Dermatitis is a chronic skin disease affecting dogs and cats. It is
believed this condition is caused by a long lasting allergic reaction to a food product.
The most common allergens are those that your pet is fed frequently. There is no
correlation between the quality of the diet and an allergic reaction. Food allergy
reactions are most commonly to a protein source (Chicken, Beef, Soy, Egg, etc.), but
could also be to a carbohydrate or rarely, to a preservative.
Clinical Signs
Dogs and cats with Food Allergy Dermatitis are most commonly pruritic (itchy)
year round, but may have gastrointestinal signs as well (diarrhea, vomiting, excessive
flatulence etc.) They will usually rub their faces, chew at their feet and may have
recurrent skin infections. Red, painful ears and recurrent ear infections are also
commonly seen. Onset of food allergy can be sudden and continues as long as the
offending food source is ingested. Once a pet is allergic to a food product, it may take
weeks to months for the clinical signs to resolve once the allergenic product is removed
from the pet’s diet.
Diagnosis and Treatment
Unfortunately, there are no reliable skin or blood tests currently available. Thus,
Food Allergy Dermatitis is diagnosed by doing an elimination diet. An elimination diet
consists of a homemade or a commercial diet that contains a protein and a carbohydrate
that your pet has never been exposed to. Alternatively, there are newer “low molecular
weight” diets that contain more common ingredients that have been molecularly altered
to be below the allergenic threshold. These and other diets used to diagnose food allergy
are veterinary prescription only diets and must be used under the supervision of a
veterinarian. The elimination diet must be very strict and your pet cannot have any treats,
raw hide, pigs ear or other animal product chew toys. Additionally, your pet may not
take any flavored vitamin products, flavored heartworm preventative, use toothpaste or
other flavored medication or products. Your pet should only be allowed to eat the
prescribed diet and drink water. NOTHING ELSE SHOULD PASS YOUR PET’S LIPS!
This diet trial will be continued for 8-10 weeks, at which point you should have you pet
rechecked and discuss the diet trial with your veterinarian.
In order to prove food allergy, a “diet challenge” is performed. You will be
instructed to begin feeding your pet the original diet plus any treats etc. If your pet is
food allergic, the clinical signs should worsen within hours to days of beginning the
previous diet. Should this happen, your pet will need to be fed the hypoallergenic diet
again. Once the clinical signs have again resolved, (usually very rapidly), your
veterinarian will instruct you as to the next step in discovering the offending allergen.
The good news is that if your pet is food allergic we can eliminate the offending food
from your pet’s life. This will decrease or eliminate the clinical signs of food allergy.
Prognosis
Many pets with food allergy may have an “allergic personality” which
predisposes them to other allergies such as Flea Allergy Dermatitis or Atopic Dermatitis
(Environmental allergies: Pollens, molds, dust, etc.). All such pets should be kept on
strict flea control and will need to be closely watched for secondary skin infections,
increased itching or other evidence of allergic dermatitis. However, with food allergy
controlled, your pet’s itch threshold will be substantially reduced allowing your pet a
more comfortable and higher quality of life.
Recommended Diet: _____________________________________________________
Please keep a diary of any changes you may note during the diet trial. These
changes may include changes in appetite, elimination, scratching, appearance of the skin
or ears, or changes in weight. Please contact the Dermatology Service with any questions
or concerns you may have during the course of the diet trial.