When humans experience an allergic reaction, the symptoms are often obvious. Coughing or difficulty breathing, runny nose, sneezing, and hives or skin rash are often tell-tale signs of an allergic response from the body’s immune system.

Dogs can experience allergic reactions too, but the signs of an allergy aren’t always so clear, and the root cause can be difficult to pinpoint.

Allergies in dogs can be caused by environmental factors like pollen, grasses, mold and fleas. In addition, a small percentage can be caused by food, Here’s what you should know about food allergies in dogs — the signs to watch for, potential causes, and what to do about it.

What Is an Allergy?

To be a true allergy, it must cause an immune response in the body. This is when the immune system overreacts to a harmless food as though it is a harmful “invader.” The immune system releases histamines to combat the offending substance, which causes symptoms, most often itching.

Food allergies are often confused with food sensitivities or intolerances. A food intolerance is when the body just doesn’t process a food properly. Lactose intolerance is a well-known example — the body can’t process lactose, which causes gastrointestinal problems.

Intolerances or sensitivities may cause symptoms similar to an allergy, but because the immune system is not the culprit, they’re not truly allergies.

Signs of Allergies in Dogs

The majority of skin problems in dogs are related to allergies, with itchiness being the most common sign but not all are food related. Dogs with allergies often lick, chew, or scratch excessively, causing inflammation and hair loss. In some cases, excessive licking and chewing may lead to a cycle of recurring painful hot spots and skin infections.

A dog with an allergy might also experience gastrointestinal trouble like gas, diarrhea, or vomiting, respiratory issues, ear infections or other symptoms. Or they may exhibit a combination of different, seemingly unrelated symptoms.

Common signs of allergies in dogs:

- Excessive itchiness (may be localized or all over the body)
- Excessive licking, chewing, or scratching
- Red, itchy, inflamed ears, frequent head shaking
- Hair loss, red or inflamed skin
- Hives or skin rash
- Open sores or hot spots
- Rubbing face with paws or against furniture
- Coughing, wheezing, shortness of breath
- Runny, red, or itchy eyes
- Runny or stuffy nose, sneezing
- Swollen paws, excessive licking / chewing on feet
- Odor from feet or ears (due to secondary bacterial or yeast infections)
- Stomach upset, gas, vomiting, diarrhea
Food sensitivities can present with many of the same symptoms, though gastrointestinal symptoms, including diarrhea, vomiting, gas, lack of appetite, and weight loss are most common.  

What’s Causing Your Dog’s Allergies?

There are three main causes of allergies in dogs: Fleas, environmental allergens, and food.

Flea allergy dermatitis is the most common in dogs. This is caused by a reaction to flea saliva which triggers itching and skin irritation. It’s also possible for dogs to react to something in their environment like dust, mold, or pollen. Flea and environmental allergies are both much more common than food allergies, but often cause the same symptoms.

Finally, there are food allergies, which are estimated to account for 10% of allergic skin issues in dogs. Animal proteins such as beef, chicken, dairy, and eggs, are the most common culprits of  food allergies and sensitivities in dogs.

According to Tufts University, “There is nothing particularly special about these ingredients other than they have been the most common ingredients in pet foods for the past few decades” so dogs have been exposed to them frequently.

While dogs can be allergic to corn, wheat, soy and other ingredients, grains and other plant-sourced ingredients are actually less common allergens than many people believe.

What to Do If You Suspect Your Dog Has Food Allergies

The first step in providing relief for your allergic dog is identifying the offending allergen and  removing it from the environment or diet.

If your dog has fleas, or if reactions seems to occur seasonally or only in certain (indoor or outdoor) locations, the problem is likely fleas or environmental.

But if your pup is flea-free, and the itching can’t be linked to season or location, it’s time to look at food.

If a food allergy is suspected, your vet may be able to perform a test to check for food sensitivities or intolerances. They will likely also recommend a diet change.

Food Allergy Diets

It’s not uncommon for dogs to develop an allergy over time to something that they’ve frequently eaten without issue. This is where an elimination diet trial comes in, currently the best tool we have available for identifying food allergies in dogs.

An elimination trial involves feeding a diet with very limited ingredients, until allergy symptoms subside, then reintroducing ingredients one by one to identify the allergen.

Veterinarians often recommend a hydrolyzed protein diet for this purpose. These are special, prescription-only diets that have been formulated to be as non-allergenic as possible.

If a protein allergy is suspected, a novel ingredient diet might be recommended. These consist only of proteins that your dog has never previously eaten, for example, venison, rabbit, or duck instead of beef or chicken.

There are pros and cons to each, so it’s best to consult with your veterinarian.

It’s crucial that during the trial, this is the only food your dog eats  — any treats, table scraps, or other food could cause a reaction and prevent you and your vet from identifying the problem ingredient.  

Usually a food allergy trial will last at least 6-8 weeks, long enough to see an improvement in symptoms. It may take up to 12 weeks for symptoms to fully resolve. If there is no improvement, it could be your dog is still being exposed to the allergen, or that they don’t have a food allergy at all. Your vet might recommend another diet trial or further testing.

If your dog’s symptoms do disappear, you can usually begin slowly reintroducing foods (one at a time) to see if symptoms return.

Helping Your Dog with Food Allergies

Once you’ve identified the food your dog is allergic or sensitive to, you’ll want to read ingredients lists on treats and food carefully, to avoid anything your dog is sensitive to. If your dog is sensitive to grains, choosing a grain-free diet is important.

The good news is, we have more options than ever available for our sensitive pups, so finding treats and foods for food sensitivities isn’t the chore it once was.

With Puppo, we take all the guesswork out of finding food for your sensitive pup. You can receive personalized formula for your dog, packed with high-quality ingredients and delivered to your doorstep. We offer grain-free options, and you can tell us which proteins and ingredients you’d like us to include or leave out. Plus, our pet nutrition experts are always available to chat with you about your dog’s diet and health. Take our simple quiz to get started today!