[Food allergy in dog and cat]

Food allergy in the dog or cat can only be described as non-seasonal dermatitis accompanied by scratching. When the term 'food allergy' is used, an immune-mediated reaction is not always meant, although the term would suggest that it is. The frequency of occurrence of food allergy is unknown, with the literature giving widely differing percentages. Type I and type IV hypersensitivity reactions probably play a role in the pathogenesis, although a type III reaction is also thought to be involved. Gastrointestinal disturbances and skin complaints are symptoms of food allergy, and scratching is nearly always mentioned as the most common sign. The diagnosis can only be made by feeding the animal on a hypoallergic diet, which must be given for several weeks. Diagnostic tests are unreliable. The patient should not have been previously exposed to the ingredients of the hypoallergic diet. As 'home-made' diets may be deficient in minerals, vitamins, and essential amino acids, these ingredients must be supplemented if the diet is to be maintained for a long time. The prognosis of food allergy is good if the causative ingredient is identified. It is important the animals' owner is given through instruction. Medicines have little effect on food allergy.