Food allergies in dogs are a common issue, accounting for approximately 10% of all allergies in our canine companions. They are the third most prevalent cause, trailing behind flea bite allergies and atopy (inhalant allergies). Notably, these allergies are responsible for 20% of the itching and scratching behaviors observed in dogs. While the exact mechanisms of food sensitization and the subsequent antibody response in pets are not fully understood, we do have a grasp on the symptoms, diagnosis, and treatment methods.
Food Allergies vs. Intolerances
It’s crucial to differentiate between food allergies and food intolerances in dogs. Food allergies are genuine allergic reactions, characterized by itching and skin problems. In contrast, intolerances may lead to diarrhea or vomiting but do not manifest the typical signs of an allergy. Fortunately, both conditions can be managed by eliminating the problematic substances from the pet’s diet.
Common Culprit Ingredients
Research has identified certain ingredients that are more likely to provoke food allergies in dogs. The most frequent offenders are beef, dairy products, chicken, lamb, fish, chicken eggs, corn, wheat, and soy. Interestingly, these are also among the most common components in commercial dog foods, suggesting a correlation between exposure frequency and the likelihood of an allergic reaction.
Recognizing the Symptoms
Food allergy symptoms in dogs and cats often mirror those of other allergies, with itchy skin being the primary indicator. This itching typically affects the face, feet, ears, forelegs, armpits, and the anal area. Other symptoms can include recurrent ear infections, hair loss, excessive scratching, hot spots, and skin infections that reoccur after antibiotic treatment ends. In some cases, dogs with food allergies may exhibit increased bowel movement frequency.
While distinguishing food allergies from other allergic conditions based on symptoms alone can be challenging, certain signs raise suspicion. These include recurrent ear issues, particularly yeast infections; skin problems in very young dogs; year-round or winter-onset allergies; and itchy skin that doesn’t respond to steroid treatment.
Diagnosis Approach
Diagnosing food allergies is straightforward but requires ruling out other potential causes first, such as atopy, flea bite allergies, intestinal parasites, sarcoptic mange, and infections. Once other issues are addressed, a food trial can be conducted.
Food Trials and Elimination Diets
A food trial involves feeding the pet a novel protein and carbohydrate source for at least 12 weeks. Examples of novel sources are rabbit and rice or venison and potato. Commercially available ‘limited antigen’ or ‘hydrolyzed protein’ diets can also be used. Homemade diets should be carefully controlled and be the only food source for the pet during this period, with no treats or flavored medications allowed. If symptoms improve, a return to the original diet (provocative testing) can confirm the diagnosis. If symptoms persist despite suspicion, a different novel food source can be tried.
Blood Testing
Blood tests are not reliable for diagnosing food allergies in pets. Veterinary dermatologists unanimously recommend food trials as the only effective diagnostic method. Intradermal skin testing is useful for atopy but not for food allergies.
Treatment Strategies
Avoidance is the primary treatment for food allergies. Once the allergens are identified through a food trial, they must be eliminated from the pet’s diet. Short-term relief can be achieved with fatty acids, antihistamines, and steroids, but long-term management requires dietary exclusion of the allergens.
Pet owners can opt for a special commercial diet or a homemade one. Homemade diets should be periodically tested with new ingredients to identify the allergens. It’s essential that homemade diets are nutritionally balanced and developed with the help of a veterinary nutritionist. Be aware that pets may develop new food allergies over time, so consult your veterinarian if symptoms reappear.