Some animals have the potential to develop a specific sensitivity (allergy) to a component of their diet. They are not allergic to a particular brand of food, but to a particular ingredient in the food. Usually they are allergic to an animal protein, such as beef, dairy, chicken or eggs, but they can also be allergic to vegetable proteins (wheat, corn, soy) or a chemical such as a preservative, stabilizer or food dye. Pets are not born with food allergies. More commonly, these allergies develop gradually to food products they have eaten for a long time.
The most common sign of a food allergy is itching. The animal may scratch anywhere on its body. You may notice hair loss or redness of the skin. There may be crusts or pustules. Many cases are complicated by bacterial or yeast skin infections. Ear infections are another common problem in food allergic patients. Some develop upset stomachs with vomiting or diarrhea. The condition can occur at any time of the year and the reaction can be immediate (within minutes to a few hours after eating) or delayed (within several hours to days).
Diagnosis of food hypersensitivity is difficult and requires feeding a non-allergenic diet, and gradually adding and deleting foods suspected of causing a reaction. We recommend testing for food allergy when the clinical signs have been present for several months, when the dog has a poor response to steroids, or when a very young dog itches without other apparent causes of allergy. Testing is done with a special hypoallergenic diet. Because it takes at least 8 weeks for all other food products to get out of the system, the dog must eat the special diet exclusively for 8-12 weeks (or more). If positive response occurs, you will be instructed on how to proceed. If the diet is not fed exclusively, it will not be a meaningful test. We cannot overemphasize this. If any types of table food, treats or vitamins are given, these must be discontinued during the testing period. There may be problems with chewable medications, as well. Your veterinarian will discuss this with you. When the offending material can be identified, the outlook for control is excellent.
Important Points in Treatment
- The diagnosis of a food allergy is made by feeding your animal a type of food that he has never had before. Unfortunately, one cannot simply switch brands of commercial dog food since most over-the-counter foods share similar ingredients (protein sources, dyes, preservatives and stabilizers). Grain-free diets are not the same as hypoallergenic diets.
- During the food trial, it is very important that you adhere to the following guidelines:
- It is very important to emphasize that your animal not be allowed to put anything into his mouth except the prescribed diet and water. This means:
- NO vitamins
- NO edible chew toys (squeaky toys and toy ropes are OK)
- NO biscuits
- NO rawhides
- NO raiding the kitty litter box
- NO table foods (this means you, grandma!)
- NO chewable heartworm prevention or other medications (Please discuss with us)
- NOTHING but the diet and water!!!!
- If your pet does manage to obtain any other food, it may be necessary to restart the entire process again.
- Occasionally, a change in diet may cause vomiting or diarrhea. Your pet may refuse to eat the diet. You may try a gradual transition to the new diet over 3-4 days, but then feed to new food only. If you have any problems, please call. Do not give up.
- In order to determine if you pet has a food allergy, this diet must be strictly maintained for 8-12 weeks. Please contact us before you change your pet’s diet, whether improvement is noted or not.
- You may not see complete relief from itching, scratching and licking, but you should see some improvement. Sometimes there will be other allergies in addition to the food allergy. It is very important to keep a DAILY ITCH diary. Note if the amount of itch is mild, moderate or severe, and any other pertinent information.
- If a good response is obtained, a food challenge could be considered, in order to determine exactly what it is you pet is causing the allergic reaction.