Veterinarians are increasingly turning to diagnostic food trials as a method to identify food allergies in pets, particularly dogs and cats. This process involves a strict eight-week period during which pet owners must adhere to a carefully controlled diet, eliminating all other food sources. While this trial can lead to significant improvements in the health of affected animals, it poses challenges for their owners, who must resist the temptation to offer alternative treats.
Pets suffering from recurrent conditions such as otitis externa, superficial pyoderma, or Malassezia dermatitis are often candidates for these food trials. Dogs with localized itching and cats displaying skin irritations may also benefit from this diagnostic approach.
Understanding the Food Trial Process
The fundamental aspect of a food trial is its rigorous nature. Currently, there are no reliable serological or allergy tests that can effectively diagnose food allergies in pets. Although some dogs may exhibit type I hypersensitivity reactions suitable for serum IgE testing, a larger number respond with type IV hypersensitivity reactions. The latter cannot be diagnosed using serum tests. As a result, the only validated method for diagnosing food allergies in dogs and cats remains a restricted diet over an eight-week period.
During this trial, pets are fed a singular, carefully selected diet, with no additional foods, treats, or flavored medications allowed. According to veterinary studies, approximately 95% of dogs and over 90% of cats respond positively by the end of this trial. In certain cases, the use of anti-inflammatory medications can expedite this response, reducing the observation period to as little as four to six weeks.
Navigating Dietary Selections
Choosing the right diet for these trials can be difficult. Common allergens for dogs include beef, dairy, chicken, wheat, corn, and soy, while cats often react to beef, fish, and chicken. Recent research indicates that cross-reactivity among proteins can complicate matters. For instance, dogs allergic to chicken may also react to fish proteins.
To address these challenges, hydrolyzed protein diets have gained popularity. These diets feature proteins broken down into smaller components, reducing the likelihood of allergic reactions. Examples include Royal Canin Ultamino®, Purina Elemental®, and Farmina VetLife Derma HF®. Successful completion of an eight-week trial with one of these diets allows veterinarians to confirm a food allergy diagnosis.
The conclusive diagnosis is typically made through a dietary provocative challenge, where the original diet is reintroduced for up to two weeks. Recurrence of previous symptoms during this phase confirms the allergy. Type I reactions may manifest quickly, while type IV reactions can take longer to appear.
Educating pet owners is crucial to ensure compliance and success during the food trial. By preparing owners with the necessary information and support, veterinarians can help streamline the process, ultimately leading to better health outcomes for pets.
Veterinary professionals like Stephanie Bruner, DVM, DACVD highlight the importance of these food trials in diagnosing and managing food allergies in companion animals. As research continues to evolve, these trials remain a cornerstone in veterinary dermatology and allergy management.
