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Table of Contents
Causes of food allergies
Food allergies occur when the body’s immune system identifies a harmless substance as a threat. The body then mounts an immune response, leading to inflammation and associated symptoms. The foods your pet eats every day can sometimes be the source of the problem. In both dogs and cats, certain proteins most commonly trigger allergic reactions. The usual suspects include beef, chicken, and dairy products in dogs and beef, fish, and dairy in cats. However, any food ingredient has the potential to be an allergen. Food allergies can develop even if your pet has been eating the same diet long-term without issue, and are often a result of genetic predisposition.
Symptoms of food allergies in dogs and cats
Food allergies may cause a combination of skin and gastrointestinal symptoms, including:
Skin Problems
- Persistent itching (pruritus) – especially around the paws, ears, and anal area in dogs and the head and neck in cats
- Skin lesions – redness, inflammation, crusting, scabbing
- Recurrent skin and ear infections
- Hair loss
- Hot spots
Tummy Troubles
- Vomiting
- Diarrhea
- Increased gas
- Weight loss
Other Symptoms
- Behavioral changes – increased or decreased energy level, aggression, hyperactivity
- Concurrent allergies – pets with food allergies may also have other types of allergies, such as flea allergies and atopy.
How to diagnose food allergies – the diet trial
Many of the symptoms of food allergies overlap with other conditions. Therefore, it can take some trial and error to arrive at a diagnosis. In general, food allergies are less common than other types of allergies in both dogs and cats. Many dogs and cats also have more than one type of allergy. Your vet may take the following into consideration:
- Is there a seasonal pattern? – Food allergies generally cause symptoms that occur year-round, whereas some environmental allergies can have a seasonal pattern.
- Response to treatment – Certain medications, such as corticosteroids, are extremely effective at managing the symptoms of environmental allergies but may not make a difference in pets with food allergies.
- Flea prevention – To rule out flea allergies, it is also critical to make sure that all pets in your household are on good flea prevention year-round.
- Symptoms – Accompanying gastrointestinal signs occur in 30% of animals with food allergies. The distribution of itchy skin and skin lesions can also help provide a clue as to the underlying cause.
Blood and skin allergy tests are not typically reliable for diagnosing food allergies in pets. The most reliable method is an elimination diet trial done under your veterinarian’s guidance. During this three-month diet trial, your pet will switch to a diet with new protein and carbohydrate sources that they haven’t eaten before. This usually involves a prescription hydrolyzed protein diet, in which the protein source is broken down into pieces so small that the body will not recognize or react to it. It is important to stick to the diet for 12 weeks – during this time, your pet cannot eat anything else (no treats, table scraps, or flavored medications).
If symptoms clear up on the new diet, you can carefully reintroduce your pet’s old food to see if problems return – this confirms the diagnosis. Or you can simply continue the new diet long-term.
While it may be tempting, it is best not to change your pet’s diet without veterinary guidance. Over-the-counter diets, even those advertised as limited ingredients or hypoallergenic, are often contaminated with additional protein sources. Additionally, grain-free diets have been linked to heart disease. It is also important to make sure that the food that you choose is complete and balanced, appropriate for your pet’s life stage, and WSAVA compliant.
Treatment for food allergies
While there is no cure for food allergies, treatment and management involve avoiding the problem ingredient(s). In many cases, it is easiest to continue feeding a hydrolyzed protein diet long-term. Sometimes, additional medications may be needed to manage your pet’s symptoms, particularly for itching or secondary skin and ear infections.
FAQ
The most common signs of food allergies in pets include persistent itching, rashes, skin infections, hair loss, and recurring ear infections. Digestive problems like vomiting, diarrhea, gas, or weight loss can also indicate a food allergy. If you notice any of these symptoms, it’s important to consult your veterinarian. They will help rule out other potential causes for your pet’s discomfort and can discuss whether an elimination diet trial is the right step to diagnose a food allergy.
If a strict elimination diet trial doesn’t improve your pet’s symptoms after the recommended duration (usually 8-12 weeks), there are a few possibilities to consider. Firstly, your pet might not have a food allergy, and their symptoms could be due to other conditions like environmental allergies, parasites, or underlying diseases. Secondly, it’s essential to ensure your pet consumed only the prescribed diet and nothing else during the trial. Hidden treats, table scraps, or flavored medications can all interfere with the results. Finally, even with a successful diet trial, secondary issues like skin infections will also need to be treated for symptoms to resolve. Your veterinarian might recommend additional medications or supplements. If a diet trial isn’t successful, always have a follow-up conversation with your veterinarian to review these possibilities and determine the best path forward for managing your pet’s health, such as a consultation with a board-certified veterinary dermatologist.
Both are types of adverse food reactions and can cause similar symptoms, however, food intolerances don’t involve the immune system.
Even with the best care, some pets, due to a combination of genetics and other factors, will develop food allergies. While prevention might not be in our control, early diagnosis and appropriate management of food allergies are essential for minimizing symptoms and helping your pet live a comfortable life.
