Food Allergies

Food Allergies

Food allergies are caused by an immunologic reaction, usually to a certain protein in a food or food additive. 

They can develop in any breed or sex and at any age. The allergy can be to a major dietary ingredient, such as beef, or a minor additive, such as a dye or preservative.

Diagnosis of food allergies in small animals can be difficult. Most animals have pruritus (itching) without any association to a specific season. Many develop subsequent secondary bacterial and/or yeast infections from inflammation of the skin and self-trauma. Owners often notice hair loss, redness of the skin, and other signs such as scratching, chewing or rubbing. About 10-15% of dogs with food allergies will have gastrointestinal issues such as vomiting, diarrhea, or gas as well.

If a food allergy is suspected, blood may be drawn and submitted for a food allergy panel. This allows us look at levels

of an antibody called IgE to certain food ingredients. While not perfect, it gives guidance for what foods to avoid.

The gold standard for food allergy diagnosis is a dietary trial with a prescription hypoallergenic diet for at least 12 weeks. These have been hydrolyzed, meaning that their proteins have been broken down to a state the body cannot recognize as an allergen. Prescription diets are usually recommended instead of an over-the-counter diet, which can be contaminated with proteins of an allergen during production. Strict adherence to the dietary trial is imperative. This means that your pet must ONLY be fed the prescribed food and water, nothing else. Some chewable medications can interfere with dietary trials as well, but many are not made with flavorings that contain protein.

If your pet consumes any other food than the prescribed diet the entire trial will need to be started over again. Benefit from the dietary trial is not usually seen for at least 6 weeks, but trials typically last for 12 weeks or longer. If the symptoms subside during the trial the diet can be fed long-term, or sometimes a dietary challenge is done with the previous food to see if symptoms return when that food is fed again. This solidifies the diagnosis of a food allergy.

Occasionally, an animal will have a food allergy in combination with other allergies. Consequently, it is important to note any differences in your pet’s condition while being fed the prescribed diet. Any decrease in chewing, scratching, rubbing, or any visible change in your pet’s skin should be recorded. At the end of the dietary trial we would like to reevaluate your pet’s condition. Please contact us with any questions or concerns you may have.

Examples of prescription hydrolyzed diets (many come in canned & dry formulations, but only Z/D comes in cans for cats):

Blue Buffalo HF      Hill's z/d      Purina HA      Royal Canin HP     Royal Canin Ultamino

Treats:     Hill's Hypo Treats     Royal Canin Hydrolyzed Protein Treats