A diagnostic food trial is essential for identifying food allergies in pets, particularly dogs and cats. This method requires a strict 8-week commitment, during which animal owners must adhere to specific dietary guidelines to ensure accurate results. Although it may be challenging, following this protocol can lead to significant improvements in pets suffering from allergic reactions.
Veterinarians often recommend food trials for pets diagnosed with conditions such as recurrent otitis externa, superficial pyoderma, or Malassezia dermatitis. Dogs exhibiting symptoms like ventrally distributed and/or pedal pruritus and cats with miliary dermatitis or head and neck pruritus are prime candidates for these trials. The primary challenge lies not in identifying these candidates but in executing the test effectively.
Importance of Controlled Food Trials
Currently, no serological, intradermal, saliva, or hair tests are reliable for diagnosing food allergies in pets. While some dogs may show responses through type I hypersensitivity reactions, a significant number exhibit type IV hypersensitivity responses, rendering serum IgE testing ineffective. The only reliable method remains a controlled diet trial, during which the pet is fed a single, carefully selected diet void of any additional foods, treats, or flavored medications for a duration of 8 weeks.
Research indicates that approximately 95% of dogs and over 90% of cats respond positively to this trial by the end of the period. In some cases, the initial phase can be expedited to 4 to 6 weeks with short-term use of anti-inflammatory medications. Prednisolone or oclacitinib (Apoquel®) can be administered to help alleviate symptoms during the trial.
Choosing the Right Diet
Selecting the appropriate diet for a food trial can be complex, as proteins with molecular weights between 15 and 40 kilodaltons are common food allergens. In dogs, typical allergens include beef, dairy, chicken, wheat, corn, and soy, while cats often react to beef, fish, and chicken. Recent advances have shown that dogs allergic to chicken might also react to fish proteins and vice versa, complicating dietary selections.
The emergence of hydrolyzed protein diets has provided a viable alternative. These diets, which contain proteins less than 5 kilodaltons, are generally considered hypoallergenic. However, only a limited selection of these diets is available in the United States. Options like Royal Canin Ultamino®, Purina Elemental®, and Farmina VetLife Derma HF® meet necessary criteria for successful trials.
Pets that complete the 8-week duration on these diets can be classified as having successfully undergone a food trial. In certain situations, alternative diets may be utilized if specific challenges arise, such as palatability issues or existing co-morbidities.
Following the trial, a dietary provocative challenge can confirm the allergy diagnosis. By reintroducing the original diet for up to two weeks while monitoring for clinical signs, pet owners can observe if symptoms reoccur, thereby validating the food allergy. Type I reactions may manifest quickly, while type IV reactions could take longer to appear.
Throughout the food trial process, educating pet owners and their families on adherence to the dietary regime is crucial. Proper preparation and understanding of the trial’s importance can facilitate success, ensuring that both pets and their owners eventually enjoy a healthier and happier life together.
For further reading on this subject, consider the works of Stephanie Bruner and her colleagues, who provide extensive insights into the diagnosis and management of food allergies in pets.
