Food Allergies in Dogs: Symptoms, Causes, & Treatments

Mary Simpson
by Mary Simpson
Food allergies are common in dogs. Do you think your dog is allergic to a certain food? We talk about what you should watch for and how to treat them.

Your dog seems to be off. He’s been vomiting sporadically, has been scratching his ears, and seems to need to be let out more than usual. Does he have food allergies or is it down to his system being overly sensitive to something he just ate? If you don’t know the difference between food intolerance and a food allergy, join the club because most pet owners aren’t sure how to read this type of diet-driven behavior either.

In a nutshell, food intolerances are fairly common in dogs and are a gradual adverse reaction he develops to one or more items in his diet such as beef, wheat, corn, eggs, soy, or milk (to name a few). The symptoms can often be similar to a true allergy, and, understandably, you may think that’s what your pet is suffering from, but the important difference is that unlike allergies, food intolerance does not involve his immune system.

When it comes to a true allergy, your dog’s body generates a hypersensitive reaction to a food item (typically a protein) that for most animals would be perfectly safe. At some point in his life, he has been exposed to this allergen and his immune system has now developed antibodies that are just waiting to kick in when he is re-exposed. When that happens, they trigger an immunologic reaction. In short, the vomiting, diarrhea, itchy skin (and more), are down to your pet’s body fighting off what it considers to be a physical threat.

Let’s look at the more common allergens, symptoms, and diagnosis options.


You might be surprised to learn that a true food allergy can crop up out of the blue after your dog has happily been noshing down on the same food, problem-free for years. And that dogs with one food allergy can often develop multiple food allergies over time. So, which are the key culprits? Research shows that the top triggers include:

  • beef
  • dairy products
  • wheat (gluten)

followed by:

  • lamb
  • chicken
  • soy
  • eggs

And while many food additives such as coloring and preservatives can provoke allergic symptoms, these are typically an intolerance.


What can make it difficult to identify an allergy from an intolerance, is that they often present with the same symptoms. They include:


  • digestive issues including vomiting and/or loose stools
  • gassiness or constantly rumbling tummy
  • dull, dry coat and/or hair loss
  • chronic scratching and/or ear infections
  • coughing, sneezing, and/or wheezing
  • discharge from the eyes

You’re going to need to involve your vet when coming up with a diagnosis that will help move your pet in the direction of better health.


There are three standard options for testing for allergies before developing a new dietary regimen for your pet. They include:

  1. Elimination diet. Your pet is fed a strict one-ingredient diet for several days, with additional food components gradually added over the ensuing weeks. It’s a wait-and-see approach that has your vet watching for an allergic reaction that will help them pin down the offending food item. It’s a lengthy process that typically takes up to 12 weeks.
  2. Blood tests. Less accurate than the elimination diet, but faster and potentially easier to change up your pet’s diet based on the results.
  3. Patch tests. Similar to the human patch test, common allergen proteins are mixed with gel and attached to exposed skin. If a reaction such as redness or hives occurs, then you’ve identified your allergen – or at least one of them.
Mary Simpson
Mary Simpson

Sharing space with three seriously judgy Schnoodles and a feline who prefers to be left alone. #LivingMyBestLife

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