Food Allergy - Diagnosis and Management

Unlike many diseases, there are no currently available laboratory or clinical tests that can be used to diagnose food allergy in dogs and cats. Both intra-dermal tests and in-vitro measurement of allergen-specific IgE are regarded as unreliable indicators of food sensitivities and cannot, at present, be recommended for use. Food allergy can only be diagnosed by properly conducted dietary trials.
Dietary trials should be performed on any dog or cat with a chronic pruritic skin disease after ruling out ectoparasites and infectious causes.
Deciding on a home-cooked or commercially available restricted diet
In the past, most veterinary dermatologists thought that home-cooked diets were preferable. Home-cooked diet trials are labour intensive and can cause problems with owner compliance. They are also not suitable for growing animals or animals already on prescription diets for other purposes. However, many dermatologists now use commercial diets for investigation of food intolerances.

Preparation and Feeding of Home-Cooked Restricted Diets 

The usual recommendation for formulating home cooked diets is to restrict the animal to one single protein source, one single carbohydrate source and water. The choice of these ingredients should be based on a detailed analysis of the animal’s previous dietary history. Typical protein sources include fish, pork, rabbit, venison, turkey, lamb, horsemeat or beans. Beef and chicken are usually avoided because these are common ingredients in commercial pet foods. Typical carbohydrate sources include potato, sweet potato, rice or pasta.
Although the individual ingredients vary in a particular diet, the preparation is fairly standard. The meat can be boiled, baked or microwaved and the carbohydrate can be boiled as usual. Excess fat should be removed from the meat as this may lead to diarrhoea. The meat and carbohydrate can then be mixed together in a blender or food processer. This provides a mixture that the animal is unable to separate. The ratio of the protein source to the carbohydrate should be about 1:2. The mixed food can then be weighed, placed in bags and frozen until required. [...]