Stan Wood, DVM, Diplomate ABVP

Specialist in Canine & Feline Practice

Food Allergy in Dogs

One of the most common conditions affecting dogs is allergy. In the allergic state, the dog's immune system "overreacts" to foreign substances (allergens or antigens) to which it is exposed. These overreactions are manifested in three ways. The most common is itching of the skin, either localized (one area) or generalized (all over the dog). Another manifestation involves the respiratory system and may result in coughing, sneezing, and/or wheezing. Sometimes, there may be an associated nasal or ocular (eye) discharge. The third manifestation involves the digestive system, resulting in vomiting or diarrhea.

Types of Allergy

There are five known types of allergies in the dog: contact, flea, food, bacterial, and inhalant. Each of these has some common expressions in dogs, and each has some unique features.

Food Allergy

A food allergy is a condition in which the body’s immune system reacts adversely to a food or an ingredient in a food.

Any food or food ingredient can cause an allergy. However, protein, usually from the meat source of the food, is the most likely offender. Proteins commonly found in dog foods are derived from beef, chicken, lamb, and horsemeat.

Lamb and Rice Diets

Although many people think lamb and rice diets are hypoallergenic, they are not. They are not inherently less likely to cause allergy than other diets. However, they have this reputation. Here is why.

Several years ago there were no dog foods on the commercial market that contained lamb. A manufacturer of prescription dog foods formulated a food from lamb that was suitable for allergy testing, which will be explained below. Because of that situation, lamb-based dog food was considered “hypoallergenic.”

Food Allergy Testing

Dogs are not likely to be born with food allergies. More commonly, they develop allergies to food products they have eaten for a long time. The allergy most frequently develops in response to the protein component of the food; for example, beef, pork, chicken, or turkey. Food allergy may produce any of the clinical signs previously discussed, including itching, digestive disorders, and respiratory distress. 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 4 weeks for all other food products to get out of the system, the dog must eat the special diet exclusively for 4-8 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 type of table food, treats or vitamins are given, they must be discontinued during the testing period. There may be problems with certain types of chewable heartworm preventative, as well. Your veterinarian will discuss this with you.

Because dogs that are being tested for inhalant allergy generally itch year round, a food allergy dietary test can be performed while the inhalant test and antigen preparation are occurring.

INSTRUCTIONS: Those instructions that are specific for your dog have been checked:

___ 1) Your dog is to exclusively eat a hypoallergenic diet. If it will not do so readily, mix it 25:75 with the current diet for several days, then gradually increase the special diet to 100%. If this does not work, contact us for an alternative plan. Discontinue any chewable treats or vitamins, including heartworm preventatives. Table food is not allowed. Offer only distilled water to drink, if that is possible.

___ 2) An injection of steroids was given. Relief should be apparent within 12-24 hours. If not, please call. The dog should feel better and itch less for about one month. If an increase in water consumption or urination occurs, please report this to us for future reference. These side effects are common with steroid administration and will go away in a few days without treatment. Return for further evaluation when the first signs of itching recur.

___ 3) Begin oral steroids when the first signs of itching return. Give ____ tablets every other morning. Adjust the dosage upward or downward to the lowest effective dose, with a maximum dose of __________ permitted. Stop giving the medication every 4-6 months to see if there are times of the year when therapy is not needed. Report any increase in water consumption to us at once.

___ 4) We have dispensed oral steroid tablets. Prednisone is most commonly used. The specific drug being dispensed for your dog is labeled on the bottle. Give ____ of the ____ mg tablets every other day for 3 doses (6 days), then ____ tablets every other day for 3 more doses (6 more days). Continue this downward progression (________________________________) until the first signs of itching recur. At that time, go back to the next higher level and report that level to us (so we can be sure it is a safe level). Stop giving the tablets every 4-6 months to see if there are periods of the year when they are not necessary. When itching returns, begin immediately at the maintenance dose. If that does not stop the itching, increase the dosage slightly (to a maximum of ___ tablets) for a few doses, then return to the lower dose. Report any increase in water consumption to us at once. (This may occur at the initial dose but should stop on the maintenance dose.)

___ 5) Your dog has a flea allergy or has enough fleas to make the other allergy problem worse. Flea control is very important and should include treating the dog and its environment. Bear in mind that flea allergies often accompany other types of allergies, especially inhalant allergy.

___ 6) Your dog has a bacterial skin infection secondary to allergy. The following are recommended:

a) Antibiotics are to be used for the next _____ days. If the infection is not gone by the time the medication is completed, call for a refill or for a change in medication.

b) The medicated shampoo,_____________________, is to be used every _____ days. Allow the shampoo to stay in the haircoat for a few minutes before thoroughly rinsing the dog.

c) The topical medication, _____________________, is to be used ______ times daily for __________ days.