By Dr Joanna De Klerk
Have you ever wondered whether your pet has a food allergy? Do they get itchy or get diarrhoea on a certain brand of food? Or have you ever wondered what the hypoallergenic cat food or dog food on the pet store shelf is for? In this article, we will explore what food allergies are, and how to care for your furry friend if a certain food doesn’t seem to agree with them.
What is a Food Allergy?
You might have heard the terms ‘food allergies’ and ‘food intolerances’ being thrown about by vets and pet owners, so it’s easy to get confused about the terminology. Simply put, a food allergy involves the immune system, whereas food intolerance is a local reaction in the guts to the food.
However, it’s not essential to get into the details of how to figure out which one your pet might have, as both are usually caused by the same thing, and treated in the same way. In this article, even though we talk about food allergies, you can consider food intolerances to be included too.
A food allergy usually only becomes apparent when your pet reaches adulthood, on average around the age of two or three years old. Therefore, your cute little fluffball is unlikely to experience an allergy at a very young age. They are also unlikely to show an allergic reaction the first time you give them a new food, as it requires several exposures before symptoms become apparent.
Food allergies can also display many different symptoms. So just because your neighbour’s dog gets diarrhoea when they have chicken, doesn’t mean your dog’s itchy skin couldn’t also be caused by a chicken allergy.
It’s important to work with your veterinarian to get to the root of your furbaby’s symptoms, as other conditions, as well as environmental allergies, can have identical symptoms. You wouldn’t want something to go undiagnosed and mistreated. Also food allergies only account for 1% of pet allergies, so it’s not something that should immediately be assumed, and other causes should be ruled out first.
What Causes Food Allergies?
So firstly, let’s address why your beloved pet might have a food allergy. Unfortunately, nobody knows for certain why food allergies occur. It is assumed there is a genetic element, but frequently, it’s simply a bit of bad luck. If your pet has environmental allergies, or is allergic to flea bites, they are also at a higher risk of having food allergies too, as it’s common to be allergic to more than one thing.
But what exactly is it that pets are allergic to in food? Most often it is the protein component. Proteins are coated in tiny molecular structures call antigens, which antibodies (part of the immune system) attach to. When an antibody attaches to an antigen, it signals for the body to try to destroy it, which can create an inflammatory reaction. For most pets, they do not have antibodies which attach to food protein antigens. But pets with food allergies have antibodies which incorrectly identify food proteins as a threat, and as a result, an inflammatory reaction takes place, either directly in the guts, in the skin, or more rarely in the respiratory system.
The most common proteins related to allergies are coincidentally the most common proteins in pet food; chicken, beef and lamb. It can be hard to avoid these, but you do have options, which we will discuss later. And remember, it requires multiple exposures for an allergy to develop, so just because your furbaby has been fed beef for years, doesn’t rule it out as a culprit.
There has been much discussion over the years about whether or not dogs can be allergic to grains. You may have even noticed numerous grain-free options when buying food. This is a topic debated by many, but it is now believed that grain allergies don’t exist, and grain intolerances are rare. Feeding your pooch a grain-free diet when they can tolerate grains can actually be harmful to them, as heart conditions, such as dilated cardiomyopathy, can result from these diets. Therefore, in summary, grains (especially wholegrains) are healthy for your dog and not something that needs to be feared.
What are the Symptoms of Food Allergies?
The most common symptoms of food allergies in pets are:
- Vomiting or diarrhoea
- Itchy skin
- Red or inflamed skin
- Chronically inflamed ears (otitis externa)
- Coughing or sneezing
These symptoms can happen rapidly after ingestion of the food or may take several days to develop.
How do you Diagnose Food Allergies?
Food allergies are notoriously difficult to diagnose, and a lack of patience is often the reason why they are misdiagnosed or missed. The reason for this is because the only definitive way of diagnosing a food allergy is through an elimination diet. This is when a diet comprising of a novel or hydrolysed protein is fed exclusively for up to six weeks. That means no other food, no treats and no table scraps, which let’s face it, is not easy when one of the main ways we can show our furry friends love is through giving them delicious food. After a tortuous (for us) six weeks, one ingredient is introduced at a time, to gradually rule in or out potential causes.
Some people try to shortcut these six weeks by performing a blood test known as serum allergy tests (SATs). But these tests are notoriously unreliable. SATs take a measurement of IgE antibodies. However, allergen-specific IgE can also be picked up in healthy dogs, resulting in false positive results, and there is no correlation between the level of IgE antibody levels and the severity of the clinical symptoms. Therefore, the current veterinary advice is that the only reliable way to demonstrate a food allergy is with an elimination diet, despite blood tests being available.
What to Feed a Pet with a Food Allergy
Once your pet has officially been diagnosed with a food allergy, you need to find a food which he won’t react to. Sometimes that’s easy not as easy as it sounds. You might be thinking that since your pet is allergic to chicken, you can simply change to a food which contains beef. Well, sometimes that will work, but you must scrutinise the pet food ingredients first.
Just because it says beef flavour on the front of the packet, doesn’t mean the only meat in it is beef. In fact, beef simply has to be detectable in the food. To get around this, on the back of the packet is an ingredients list. Some foods will have every ingredient written in small print there, however others will simply use the terms ‘meat and meat derivatives’. These are the ones you should avoid.
An easier way to feed your pet is with a hypoallergenic or hydrolysed food. A hypoallergenic food contains novel proteins which your furry friend has probably not been exposed to before and therefore is unlikely to react to. Commonly used proteins are duck, venison and turkey. Hydrolysed food on the other hand, takes it one step further, and is the gold-standard food for allergic pets. It contains hydrolysed proteins, which are proteins that have been stripped of their antigens. As a result, the immune system doesn’t react to them at all.
Hypoallergenic treats also exist, however they are quite difficult to find, so you may find it easier to make your own treats. For example, it is easy to make liver snaps (using a liver from an animal which you know your pet is not allergic to) by boiling the liver, then cutting into tiny pieces and dehydrating them in the oven. Alternatively, you can use some pet food pellets as treats, which is what you would have done in the elimination trial anyway.
How to Care for a Pet with a Food Allergy
Once you’ve figured out which food your furry friend tolerates well, you should try to exclusively feed that food. But you’re sure to come across the occasional time when a child drops their food, a guest sneaks your pet a table scrap unknowingly, or your cheeky furbaby snatches something off the countertop. If it flares up their symptoms, you might need to take them to the vets to get some medication to bring it under control.
If your cat has a food allergy, it is also much easier to treat if they are a house cat. Outdoor cats are often fed by neighbours, or go hunting, and mice are not hypoallergenic! If your kitty will tear the house apart at the thought of being inside, you can consider placing a collar on them reading ‘do not feed me’, however this will still not prevent them from hunting.
Finally, don’t forget to check your pet food supplements for allergic ingredients too, for example fish oils may still contain fish proteins in, and many powdered joint supplements contain beef extracts to improve palatability. It will do your pet no good if you’re trying to give them an elimination diet but still give them supplements containing ingredients you are trying to avoid.
Take Home Message
Food allergies are uncommon in pets, despite them often being blamed for allergy symptoms. But if your furry friend is struggling with uncomfortable skin or dodgy guts, it is worth considering if it might be a cause. Working with your vet will help you get to the bottom of it quickly, and be able to advise you on the best food for their problem.