A retrospective study of canine food hypersensitivity was performed through the examination of clinical records of suspected dogs examined at the Serviço de Dermatologia at the Hospital Veterinário of Universidade de São Paulo in the period from 2003 to 2007. Presumptive diagnosis was achieved by association of anamnesis, clinical findings and complementary exams to rule out other skin diseases. Dogs were exclusively fed with home-made elimination diet consisting of a unique protein (lamb, fish or rabbit) and carbohydrate (whole rice of a unique protein (lamb, fish or rabbit) and carbohydrate (whole rice or potatoes) sources with addition of oil (canola, sunflower or corn), for a minimum of 8 weeks. Definitive diagnose was obtained in 69 dogs in which good response to diet represented by pruritus decrease was observed, followed by pruritus reappearance after re-exposure to former diet.

Food hypersensitivity was more common in females (68.1%), and purebred dogs (88%), especially Poodle, Dachshund, Lhasa-Apso and Boxer. An onset of clinical signs before 6 months of age was presented in 21.9% of animals and in 42.2% it occurred between 7 months and 3 years, characterizing an age predilection.

Concurrent diseases observed included pyoderma (62.9%), Malassezia dermatitis (17.7%), atopy (14.6%) and flea bite hypersensitivity (4.8%). Only 7.2% of the dogs showed gastrointestinal signs. Otitis and pododermatitis were seen in 44.9% and 43.5% of the dogs, respectively. Some of the dogs were submitted to glucocorticoid therapy and most of those (87.9%) demonstrated good response to prednisone. No dogs showed seasonality of clinical signs.

Pruritus was the main clinical feature and it was considered intense in 90.6% of the dogs. The most frequent lesions included erythema, alopecia, crusts, scales, papules and hyperpigmentation. Lesions were mainly concentrated on the head (50.7%), abdominal (68.1%) and cervicothoracic (59.4%) regions, as well as thoracic (40.6%) and hind (39.1%) limbs.

Response to elimination diet at the thirtieth day follow-up was considered poor in 34.4% of dogs, good in 23.2% and excellent in 34.4% of dogs. In 7%, no response was seen at day thirty. At the sixtieth day follow-up, 26% of the dogs showed good response and 67.4% showed excellent response to food elimination diet.

Ingredients found to be most allergenic were chicken (59.6%), beef (38.5%), dairy products (15.4%), rice (13.5%) and canine tidbits (19.2%). In a lesser proportion fish, wheat products, vegetables and additives were also found to have an allergenic role.