A food allergy or intolerance in a dog or cat: what’s the difference?

Does your dog or cat often vomit, have diarrhea, or suffer from itching and scratch a lot? There is a good chance this is caused by one or more specific ingredients in your pet’s food. This is caused by a food allergy or intolerance. Many people think these terms mean the same thing, but nothing could be further from the truth. Both are considered food sensitivities, and although the physical symptoms in pets are fairly similar, food allergies and food intolerances cause different reactions in the body. In this blog, we take a closer look at the differences.

The difference between a food allergy and a food intolerance

With both a food allergy and a food intolerance, a dog or cat reacts poorly to the food it is currently receiving. Although the symptoms are fairly similar (which makes it difficult to determine whether it is a food allergy or a food intolerance), an animal with a food intolerance mainly suffers from stomach and/or intestinal problems. Dogs and cats with a food allergy often suffer from skin and coat problems. Symptoms may include excessive shedding or a lot of dandruff, but the animal may also experience itching and scratch itself until red or bald patches appear. Sometimes the dog or cat may itch so severely that it scratches its skin open, causing scabs to form.

With a food allergy, the dog’s or cat’s immune system is always involved. In most cases, the dog’s or cat’s body reacts to a specific protein in the food, after which the animal’s body produces histamine in response to the protein. The production of histamine can cause itching, red skin, vasodilation (= widening) of the blood vessels, and possible swelling. The most common proteins in pet food that cause allergic reactions in dogs or cats are beef, chicken, wheat (gluten), dairy products, eggs, and soy. These are called allergens.

With a food intolerance, a dog’s or cat’s body reacts unusually to a specific ingredient, but the immune system is not involved. As a result, no histamine is produced. The specific substances in the food that the animal reacts to are called triggers rather than allergens. With a food intolerance, the dog’s or cat’s body is unable to digest a particular substance, which can cause gastrointestinal symptoms such as abdominal pain and/or diarrhea.

How does a dog or cat develop a food allergy?

Although food allergies often occur in young animals under one year old, a dog or cat does not have to be allergic to a particular protein from a young age. The animal’s body can also develop an allergic reaction later in life. Your dog or cat may have eaten the same food for years without having an allergic reaction, only to develop a food allergy to a specific protein in the food after several years. Most food allergies develop in response to ingredients that the animal consumes more frequently. The chance that a dog or cat will react to a new protein source (meaning that the animal has never consumed that protein source before) is very small. Heredity may also play a role in food allergies.

How can you find out what your dog or cat is reacting to?

It is difficult to diagnose a food allergy or intolerance because the symptoms associated with a food allergy or intolerance can also occur with other conditions. Examples include fleas, parasites, or various other allergies. Nevertheless, it is possible to determine exactly what the dog or cat is reacting to. A veterinarian can perform an allergy screening using blood and hair tests. Another option is to put the dog or cat on an elimination diet. An elimination diet means that the animal is given food consisting of only one protein source, which it must receive for at least six weeks. If the dog or cat still reacts well to the food after these six weeks, the animal is not allergic to the protein source in the elimination diet. If the symptoms persist and your pet reacts poorly to the food, the animal is probably allergic to the protein source included in the food. In that case, the dog or cat should follow another elimination diet containing a different protein source. You repeat this process until you find a food that your pet responds well to.

Important! Please bear in mind that during the elimination diet, all food the animal receives may contain only one and the same protein source. This applies to dry food and wet food, but certainly also to snacks and other treats. Would you like to give your four-legged friend a snack? Then give it only a snack that contains the same single protein source as the elimination diet.