Why do some dogs develop food allergies?

Allergies of one type or another affect a significant number of dogs in the UK, and a great deal of these are apt to go undiagnosed if they are mild, do not produce a lot of obvious symptoms, or are seasonal and short-term.

While the most common variety of allergies that dogs are prone to suffering from are atopical in nature-which means allergies that are caused by triggers that are inhaled or come into contact with the skin-coming a close second is food allergies, which are almost as diverse and varied in nature!

Literally any edible product you can think of can be a potential allergen to a dog, although some ingredients are much more common to lead to allergies than others-and food allergies in dogs can be hugely variable in terms of their presentation, severity, age of onset and effects.

This causes many owners of dogs with food allergies to wonder why their dog developed the allergy in the first place, particularly if it did not develop until later in life and/or the dog’s other close relatives are unaffected.

Whilst a lot of articles are written about food allergies in terms of what type of foods cause allergies, how to identify the symptoms and how to deal with them, a lot less are devoted to looking into precisely why a dog might develop a food allergy in the first place, particularly later in life.

In this article we will attempt to answer this question, and look into the various theories and schools of thought surrounding the causes of food allergies in dogs. Read on to learn more.

The importance of allergen identification

The key to managing allergies in dogs-whether that takes the form of removing the offending ingredient from the diet, offering supportive care or medicating-involves identifying the specific allergenic trigger itself, or working out which ingredient out of the long list on the back of the food packet is the potential culprit.

Until you can identify what the allergen in question is, your attempts to manage it are likely to be reactive and only partially successful, unless you happen to strike lucky early on!

Why food allergies can be so challenging

There are many different allergens that can be a real problem to work with-such as pollen allergies, as it is virtually impossible to keep your dog from breathing in pollen out on walks, or even when they are at home. Food allergies on the other hand should theoretically be simpler, because once you have identified the allergen, you can choose a food that does not contain it.

However, if your dog’s allergy leads to mild symptoms-such as loose but not runny stools, or slight discomfort after eating that your dog can feel but you cannot see-it can be hard to even realise that something is up in the first place. Coupled with this, whilst atopic allergies can generally be traced back to a hereditary cause that will be apt to crop up regularly in related dogs (and so, often across specific breeds) food allergies are not thought to be hereditary, and are equally likely to affect any breed or type of dog.

Food allergies may not be evident from an early age either-some dogs only develop their allergy later in life, which often results in their owners trying to find out if the recipe for the dog’s food that was previously fine has recently changed, or had something added. While most dogs with food allergies will be diagnosed before they are six years old, it is entirely possible for even dogs over ten to be diagnosed with a food allergy for the first time, and this seemingly random process of targeting is actually a potential key to identifying the root cause of the allergy.

Why do food allergies develop?

Looked at from a logical layman’s point of view, it does not make much sense to think that a dog may eat a certain food for many years and be fine with it, but suddenly develop a sensitivity to it. However, while there is no universally recognised explanation as to why a dog might develop a food allergy, there are several plausible theories that bear consideration.

Firstly, dogs are most likely to develop an allergy to a food ingredient that they do not actually need to eat and would be highly unlikely to eat in the wild-such as wheat, which is used as a bulking agent in many foods, and which provides no genuine nutritional value to dogs-and which is also the most common food allergen.

Additionally, high-protein ingredients such as shellfish and beef are other things that dogs would not generally be able to catch and eat in the wild, and these are another couple of common allergens that present later in life in dogs too.

However, intestinal worms may be the ultimate key to the random onset of allergies in dogs-one school of thought is that chronic or repeated bouts of intestinal worms lower your dog’s tolerance and increase their sensitivity to allergens in general, giving what might otherwise have been a harmless ingredient, such as wheat, the potential to cause a bad reaction.

This theory also helps to explain the wide range in terms of age of onset of allergies, as dogs can of course get worms from a young age, or over the course of a long life, have been exposed to worm infestations several times.

Research is still being undertaken to get to the bottom of food allergies in dogs-and other animals-but having a good worming protocol in place for your dog is wise for a whole range of reasons-and knowing that it might help to prevent food allergies from developing in the future is just one of them!