What every dog owner should know about food allergies

Just like us, our dogs can develop a food allergy at any time of their life, and to any food, even if they have been eating the offending food for months or years with no trouble.

But what is a food allergy, and what do you need to know as a dog owner?

What is a food allergy?

A food allergy is when your dog’s immune system doesn’t work as it should and mistakes the food as a threat, even though it really isn’t.

Usually, when the immune system spots a foreign body, like a virus, it springs into action to remove it from the body. In the case of a food allergy, the body overreact and mount an immune response to the food when there is nothing harmful to defend against.

So those symptoms that you see, such as itching, runny eyes, vomiting or diarrhoea, is a side effect of the immune system doing work that really it doesn’t need to.

It is worth noting that the terms food allergy and food intolerance are often used loosely and somewhat interchangeably to describe any adverse reaction to a food. A true allergy, however, is an adverse reaction where the immune system is involved – think peanut allergy in humans.

A food intolerance is when these reactions occur without an immune component. The body can’t probably digest the food that is eaten, or the food might irritate the digestive tract. For instance, a lactose intolerance results when an individual does not have sufficient levels of lactase.

Does diagnosing the difference matter?

Since many of the symptoms of a food intolerance are similar to those caused by an allergic reaction, the simple answer is, not necessarily. The goal is to help your dog feel better

What causes a food allergy?

Allergic reactions are mostly linked to a protein source in your dog’s diet. While the most common culprits are the meat in your dog’s food, vegetables and grains are not always a safe bet as they can contain protein too.

Why proteins, you may ask? The question of what makes a protein allergenic is just one of many that researchers are still investigating. As of today, the answer would be that we still don’t know, and further research is needed

What signs should you look out for?

The most common symptoms to look out for is itchy skin, mostly around the ears, face, the feet or anal area and recurrent ear infections, or gastrointestinal issues, such as vomiting or diarrhoea. In some dogs, the consumption of the offending food(s) results in skin and intestinal disease together.

These symptoms are also quite common in other conditions such as flea bites or environmental allergens – dust mites, pollen, grasses etc, or other gut issues such as parasites, pancreatitis, or even dietary imbalances. Because of the similarities, it can be hard to diagnose which condition your dog has, but diet, medical history and clinical signs usually provide important clues for your vet or nutritional adviser.

Diagnosing a food allergy

One of the most frustrating things about food allergies is their diagnosis. There are blood, hair and saliva tests available, but they can’t precisely rule in or out ingredients. At present, the only reliable way to diagnose a food allergy is to start your dog on a food elimination trial.

In short, this involves removing all of the currently fed foods and start your dog on a simple diet made up of a combination of one protein and one carbohydrate that your dog has never eaten before. This diet must be fed for a minimum of 8 weeks before slowly introducing new ingredients one by one.

Is there a cure for food allergies?

Not yet! The only way to treat food allergies is avoidance. Currently, there is no evidence that dogs can outgrow their food allergies, so once a food substance has been identified, the condition is considered lifelong.

However, the outlook for dogs with a food allergy is usually very good and can be managed through diet. The main goal is to identify the ingredient responsible for the adverse reaction and remove it.

Over the counter foods – don’t be fooled

If you want to manage your dog’s diet using ‘over-the-counter’ foods, then there are a few things to be aware of. Many wet and dry dog foods labelled as ‘hypoallergenic’ or ‘limited protein’ are unlikely to be truly hypoallergenic. Any individual dog could be allergic to any protein source, so there is no guarantee that the ingredient(s) that causes discomfort for your dog is eliminated from the product.

Additionally, a recent survey found that as many as 77% of protein diets were mislabelled and contained undeclared proteins. Perhaps an alternative option using fresh food might be a safer bet.


Any breed can be affected by food allergies at any age, so if you think your dog is suffering with allergies or potential symptoms of an allergic reaction, please make a visit to your vet, not your local pet store.

Many of the symptoms that are linked to food allergies can also be caused by the environment or other more temporary conditions. It is important to identify the type of allergy that your dog may be suffering from before changing your dog’s diet, to avoid wasting time and money on the wrong course of treatment.