The good news for most dog owners is that food allergies in dogs are rare. Only two out of 1,000 dogs suffer from some type of food allergy.
The bad news is if your dog is one of the unlucky few with a food allergy, you’re both in for a lot of discomfort.
For your dog, itchy skin, ear infections, vomiting, or diarrhea. For you, the powerless feeling of not being able to help your dog get better.
Part of the problem is determining whether your dog actually has a food allergy. Or whether her symptoms are due to something else, like an environmental allergy or underlying health issue.
So, how can you tell if your dog is allergic to food?
Before we get into the symptoms of food allergies in dogs, a quick note on the difference between a food allergy and an intolerance. Though the terms are used interchangeably, scientifically, they’re different.
A food allergy is an adverse reaction triggered by an immune system-based response. Food intolerances are adverse reactions not related to the immune system.
(Learn about common dog allergies and their symptoms.)
As an example, a dog that is lactose intolerant is missing the digestive enzyme needed to digest foods that have lactose. That’s not an allergy. But he’ll still have an adverse gastrointestinal reaction to anything with lactose.
In a dog with a true allergy, the immune system has decided that something is a threat – say, a protein found in chicken. The reaction, caused by the immune system creating antibodies to fight off the threat, is almost always exaggerated. Food allergies typically manifest as a skin problem like itchiness or hair loss. But allergic reactions can also be gastrointestinal in nature.
Though medically different, for most practical purposes, food allergies and intolerances in dogs are the same. The symptoms are usually identical. And the best solution – eliminating the food item causing the problem – is the same, as well.
However, there are ways to treat food allergies in dogs that won’t work for food intolerances. Dog foods low in the most common dog allergens will not help a dog with a food intolerance. Neither will a supplement designed to suppress a dog’s overactive immune system.
On the flip side, corticoid treatments may help dogs with food intolerances, but not those with food allergies.
Food allergy symptoms in dogs (and food intolerances) fall into two categories: skin problems and gastrointestinal.
Generally speaking, pure food allergies in dogs will manifest as skin problems, like pruritus (itchiness) and hair loss. Symptoms appear year-round and are typically located on the head, feet, and belly, but can also be found around the groin.
Another common symptom of dog food allergies is a type of ear infection called otitis.
(Food allergies are not the most common cause of pruritus. That’s flea allergy dermatitis. See what other common dog skin problems you need to watch out for.)
Gastrointestinal symptoms are also possible, but less common. These can include vomiting and diarrhea, as well as increased frequency of defecation and gassiness. In many cases, gastrointestinal symptoms are a sign of a food intolerance and not an allergy.
Food allergies can develop at any point in your dog’s life but generally manifest during puppyhood or mid-to-late adulthood (older than six years).
Most food allergies in dogs are to a protein or complex carbohydrate in the dog’s diet. In the majority of cases, the allergy is to an animal protein that's found in chicken, beef, dairy, and eggs.
Allergic reactions to lamb, pork, and fish are less common. The same is true of allergies to wheat and corn in dogs.
A 2016 report entitled “Critically appraised topic on adverse food reactions of companion animals,” paints a clearer picture of the most common dog food allergies. Of 297 dogs with a confirmed food allergy, the most frequently reported allergens were beef (102 dogs, 34%), dairy products (51 dogs, 17%), chicken (45 dogs, 15%), wheat (38 dogs, 13%), and lamb (14 dogs, 5%).
True dog food allergies are rarer than intolerances. According to the Pet Food Institute, a diagnosed food allergy accounts for only about 1% of all skin diseases in dogs. And a 2018 State of Pet Health Report from Banfield Pet Hospital found that true food allergies affect just 0.2% of dogs.
Food intolerance in dogs is more common.
Diagnosing food allergies in dogs is no easy task. And, it takes months to do.
That’s because the only method for diagnosing a food allergy is the process of elimination. That can mean multiple special diets as your vet works to identify the specific source of the problem. And then creating a diet your dog doesn’t react to.
Making it even more difficult, you'll need to stick to the strict diet(s) your vet prescribes the entire time. That means no treats. No leftovers. No supplements (unless prescribed by your vet). One small slipup can set the diagnosis process back weeks or even months.
And, making matters even harder, there’s always a chance your dog is allergic to more than one food. Some experts estimate up to one-third of dogs with a food allergy are allergic to more than one food.
If you think your dog has a food allergy, consult your vet for the next steps. A supplement like our Skin Health & Itch Relief might help ease mild food-based allergic reactions. But you'll be treating the symptoms and not the allergy. Allergies can get worse over time if the allergen is not eliminated. If you notice your dog’s symptoms worsen, call your vet right away.