Veterinarians are emphasizing the importance of conducting proper diagnostic food trials to identify food allergies in pets. These trials can be emotionally taxing for pet owners, demanding strict adherence to dietary restrictions over an eight-week period. While pet owners might struggle with the temptation to offer their animals treats, successfully implementing these trials is crucial for diagnosing conditions such as recurrent otitis externa, Malassezia dermatitis, and various forms of dermatitis seen in both dogs and cats.
Food trials are the only reliable method for diagnosing food allergies in pets. According to recent studies, approximately 95% of dogs and over 90% of cats respond positively to a controlled diet after eight weeks. This response rate underscores the significance of a dedicated approach to eliminating potential allergens from a pet’s diet.
Challenges in Conducting Food Trials
One of the major hurdles in conducting a food trial is the strict dietary regime that must be adhered to. During the trial, pets should consume only one carefully selected diet without any other foods, treats, or flavored medications. This restriction can be difficult for pet owners, especially when faced with pleading eyes from their pets. Pet owners can enhance compliance by educating family members about the importance of following the trial guidelines.
Veterinarians often recommend short-term use of anti-inflammatory medications, such as Prednisolone or Oclacitinib (Apoquel®), to help alleviate symptoms during the trial. This can reduce the time needed to observe improvement, potentially shortening the trial duration to 4 to 6 weeks.
Selecting the Right Diet
Choosing the right diet for the trial is critical. Proteins with molecular weights between 15 and 40 kilodaltons are common food allergens for both dogs and cats. In dogs, allergens frequently include beef, dairy, chicken, wheat, corn, and soy, while cats are commonly affected by beef, fish, and chicken.
Recent advancements in molecular allergology have revealed that pets allergic to chicken may also experience cross-reactivity with fish proteins. Similarly, dogs with beef allergies might react to other ruminant proteins such as lamb or bison. This complexity makes it increasingly essential to select diets carefully, taking into account the potential for protein cross-reactivity and unknown dietary histories, particularly in rescue animals.
Hydrolyzed protein diets have emerged as a popular option due to their lower likelihood of provoking allergic reactions. Diets like Royal Canin Ultamino®, Purina Elemental®, and Farmina VetLife Derma HF® are among those that meet the criteria for a successful food trial. For pets that struggle with palatability or have multiple health conditions, alternative diets may be considered on a case-by-case basis.
The definitive diagnosis of food allergies ideally follows a dietary provocative challenge. This involves reintroducing the original diet for up to two weeks while maintaining all other variables constant. If prior symptoms recur, it confirms the presence of a food allergy. Type I reactions may manifest within hours to days, while Type IV reactions could take longer, appearing between 4 and 12 days after exposure.
Educating pet owners and their families about the food trial rules remains vital throughout this process. With the right preparation and empathy, veterinarians can help ensure that both pets and their owners successfully navigate this challenging but necessary journey toward improved health.
By Stephanie Bruner, DVM, DACVD
Recommended Reading:
– Fernandez-Lozano C, Mas-Fontao A, et al. Evaluation of a direct lymphocyte proliferation test for the diagnosis of canine food allergies with delayed reactions after oral food challenge. Vet Dermatol. March 2025; 36: 433–442. doi: 10.1111/vde.13312
– Jackson HA. Food allergy in dogs and cats; current perspectives on etiology, diagnosis, and management. J Am Vet Med Assoc. March 18, 2023; 261(S1): S23-S29. doi: 10.2460/javma.22.12.0548
– Jackson HA, Dembele V. Conducting a successful diet trial for the diagnosis of food allergy in dogs and cats. Vet Dermatol. 2024; 35: 586–592. doi: 10.1111/vde.13274