Food Allergies in Dogs: Signs and Treatment Options

Dogs can have all the same sensitivities and allergies as humans (except being allergic to dogs, of course). Some of their symptoms are even the same, including itchy rashes and diarrhea. When it comes to food allergies, the treatment is even the same in dogs as for people: avoid all traces of the food allergen. Unfortunately, figuring out what is causing your dog’s symptoms can be frustrating, and it is disheartening to watch your dog be uncomfortable. 

Hopefully with a little background information on food allergies in dogs and lots of direction and guidance from your veterinarian, you can help your dog feel great again.

Can Dogs Be Allergic to Food?

Yes! Just like people can be allergic to food, so can dogs. The most common food allergens in dogs are animal proteins. Specifically, chicken, beef, and dairy are most likely to cause a reaction in a dog. Dogs can be allergic to any protein, including egg, fish, seafood, soy, lamb, and even venison. Just like humans, some dogs have gluten allergy (wheat protein), but this is much less common than gluten sensitivity in people. 

What Causes Food Allergies in Dogs?

While we don’t know exactly what causes food allergies in dogs, we do know that there is at least some inherited component. That is because German Shepherd dogs, West Highland White Terriers, and Labrador and Golden Retrievers are more likely to have food allergies than other breeds (1). The predisposition in Labrador and Golden Retrievers is so great that even their mixes such as Labradoodles and Goldendoodles have high rates of allergies. 

Most allergic reactions are due to an overactive immune system response. In a food allergy, the immune system doesn’t recognize a protein as food. Instead, it thinks the food protein is harmful and mounts a response. Just as for some people shrimp is a tasty food while for others even the tiniest bite can send them to the hospital. This response is what causes symptoms. Symptoms of food allergies in dogs tend to involve the skin and the gastrointestinal tract (stomach and intestines). 

Can dogs develop food allergies later in life? 

Most food allergies in dogs start to become apparent between 6 to 12 months of age (1). However, dogs with minor sensitivities can develop more severe allergic responses to foods as they age. For dogs with environmental allergies, it can be difficult to distinguish signs of food allergy until the environmental allergies have been addressed. This is because they overlap in symptoms and many dogs have more than one type of allergy. In addition to food and environmental allergies, the third common type of allergy in dogs is to fleas.

Dog Food Allergy Symptoms

The most common symptoms of food allergy in dogs are related to digestion and to skin. Dogs with food allergies may have chronic or recurrent diarrhea. Vomiting is a more rare but more severe symptom of food allergy. Some dogs may not want to eat their food if they associate it with a stomach ache. Dogs also show signs of food allergies on their skin. They may lick their feet excessively and cause irritation or swelling between their toes. They may have itchy ears and suffer from frequent ear infections. In fact, ear infections in young healthy dogs are often the first sign a veterinarian has that a dog may suffer from allergies of any kind. 

Common symptoms of food allergy in dogs:

• Diarrhea
• Decreased appetite
• Weight loss
• Licking feet
• Swollen feet
• Itchy ears
• Itchy skin
• Ear infections
• Vomiting 

How to Diagnose a Dog Food Allergy 

Research shows that neither blood nor saliva tests are valid for diagnosing food allergies in dogs (2). Therefore, an elimination diet trial is the best way to diagnose food allergies in dogs. The concept sounds simple: If you can completely exclude the offending allergen(s) from your dog’s diet, then your pet’s symptoms should resolve. However, an elimination diet for dogs is hard to do properly.

The first step is the easy part: You and your veterinarian will select an appropriate food for the elimination diet trial. Options include:

Hydrolyzed protein dog food. Hydrolyzed means that the protein source in the food is broken down during processing so that the body no longer recognizes the protein as an allergen. Hydrolyzed protein diets are the best food for dogs with allergies. Hydrolyzed diets such as Royal Canin Ultamino are the gold standard tool for elimination food trials. 

Novel protein dog food. For some dogs (young and with a fully known diet history), a novel protein diet is also an appropriate choice to avoid allergens. Novel means your dog has never been exposed to that particular protein before. Examples of novel proteins include venison, rabbit, and kangaroo. However, diets with similar proteins — think chicken and turkey or beef and bison — may cross-react, so these may not be suitable options. 

Limited-ingredient dog food. As the name implies, limited-ingredient dog foods have fewer ingredients than traditional dog foods. They typically contain a single protein source, limited carbohydrates, and no fillers. The recipe may use a novel protein source as described above. However, a complicating factor is that not all limited-ingredient diets are free from cross-contamination with potential allergens. Prescription limited-ingredient diets tend to be the only ones able to guarantee against cross-contamination.

Once you and your veterinarian have selected the food, the hard work begins at home. You, other members of your household, and visitors should NOT feed your dog anything other than the recommended diet. This means no treats, snacks, table scraps, or medications or supplements that contain food proteins. This can be challenging, especially in homes with multiple dogs. You will need to feed your other dogs separately, or else all of your dogs will need to eat the same elimination diet. If you accidentally let your dog eat something outside of their prescribed diet, you will need to start the entire trial timeline over again.

Even medications and supplements that contain food-based ingredients should be avoided. This may mean using a different monthly heartworm preventative, such as a topical treatment, during your dog’s diet trials. Any flavored tablet could contain what your dog is allergic to. Talk to your veterinarian about every medication and supplement your dog is on.  

It can take up to 12 weeks after switching your dog’s food for allergy symptoms to go away. For this reason, diet trials typically last four to 12 weeks. Your veterinarian will evaluate your dog every two to four weeks. Make sure to keep a record of your dog’s symptoms at home so you can discuss their progress during these vet visits. Keep in mind that some dogs respond to diet trials quickly while others take longer. The trial will conclude once your dog improves or at least 12 weeks have passed without any progress and your veterinarian has evaluated your dog. If your dog responds to the trial, their gastrointestinal signs will typically improve first before their skin signs improve.  

Once all symptoms have resolved, your veterinarian will direct you to add back in one protein at a time, called a food challenge. It might be chicken one week and then beef two weeks later. It is important to give each protein time to cause a reaction and detectable symptoms before moving on to the next food challenge. Your veterinarian will direct you on how to monitor for a reaction and how to proceed.

How to Treat Dog Food Allergies

The best way to treat a dog food allergy is to completely eliminate the offending allergen from your dog’s environment. You will need to feed your dog a hydrolyzed protein, limited-ingredient, or novel protein diet, and ensure that your dog’s treats, dental chews, medications, etc., are also allergen-free. Do not feed your dog table scraps or let them lick dishes in the dishwasher. 

Aside from looking at the main ingredients in your dog’s food, you need to consider the risk of cross-contamination with other proteins. Unlike human food, dog foods are not required to state possible allergen contaminations on the packaging. For example, foods may be labeled as being made in a facility that processes peanuts. Very few pet food companies can guarantee against cross-contamination for their limited-ingredient diets. This is because it is time-consuming and expensive to shut down facilities and deep clean between making different products The few companies that do make this guarantee include Royal Canin, Hill’s, Purina, and Eukanuba. These are usually prescription diets that can be labeled as a treatment for your dog’s allergies. 

It is not worth risking your dog’s discomfort by feeding something that may only be partially effective. For dogs with food allergies, food is medicine. Yes, allergen-free prescription dog food costs more money than most other dog food. Trying to save a few dollars by continuing to expose your dog to even low levels of their allergen may not cause a reaction at first. But symptoms can worsen over time, causing unnecessary discomfort to your dog (and expense of treating the skin issues).

While your regular veterinarian can diagnose a dog food allergy and conduct a dog food trial, veterinary dermatologists are often the best resource since they specialize in diagnosing and treating allergic diseases in dogs.

Your dog is unlikely to need medication for food allergies, so long as you maintain their allergen-free diet. If your dog’s symptoms flare-up, then your veterinarian may prescribe a short course of medication to help them feel better while also reinforcing the need to stick to an allergen-free diet.

A food allergy is only one of many causes of dog itchy skin or GI discomfort. Avoid taking matters into your own hands. Schedule an appointment with your veterinarian before switching your dog’s food or trying an elimination diet. Doing it incompletely or the wrong way first only prolongs your dog’s discomfort.

References

1. Olivry T, Mueller RS. Critically appraised topic on adverse food reactions of companion animals (7): signalment and cutaneous manifestations of dogs and cats with adverse food reactions. BMC Vet Res. 2019;15(1):140)
2. Jackson, Hilary A. “Food allergy in dogs and cats; current perspectives on etiology, diagnosis, and management.” Journal of the American Veterinary Medical Association vol. 261,S1 S23-S29. 18 Mar. 2023, doi:10.2460/javma.22.12.0548