What are dog food allergies?

Long shelves with dog food and treats line every pet shop you step into. Online pet shops are the same, with their biggest and most varied offer being for pet foods and treats. And it’s normal to be so. We’re a nurturing species and we enjoy feeding our loved ones, be they two or four-legged. But sometimes food can cause problems too, as is the case of food allergies.

What are dog food allergies?

Food allergy is a type of hypersensitivity that dogs can develop. This means that the dog’s gut immunity wrongly takes food proteins for harmful pathogens and starts producing antibodies against them, triggering a cascade of damaging effects.

Sometimes food allergies are grouped together with food intolerances under the umbrella term of Adverse Food Reactions (AFR) or Cutaneous Adverse Food Reactions (CAFR) because both are triggered by food and their symptoms are very similar. But there are a few notable differences between these two.

Food intolerances produce inflammation in the gut without antibody production, somewhat similar to human IBS. The symptoms appear from the very first time that the pet has the offending ingredient(s). These can also be very variable - proteins, carbohydrates, fats, various food colourants or additives or components that form during processing. Therefore the quality of food plays a role in intolerances. Intolerance symptoms appear quickly, but also resolve rapidly when the food is not fed anymore.

Food allergies involve the immune system, which produces allergen-specific antibodies. They develop slower in time, when your pet has had the same food for a long period of time. Sometimes it may take over 1 year before they manifest. The symptoms due to an allergy then also take longer to fade after the allergenic food is stopped. The quality of food ingredients plays almost no role here. That is, a dog allergic to chicken will be equally allergic to chicken from intensive farming or the most naturally and organically reared birds.

Needless to say, a food allergy can be triggered not only by dog food, the allergens could be in anything your dog eats, including treats and anything hunted or scavenged outdoors.

Dogs of any age can get food allergies, from recently weaned puppies to old dogs that have had the same food for years. But symptoms are more likely in young dogs - roughly 30% of dogs that are diagnosed with food allergy are under 1 year old. There’s no difference between males and females or any breed predisposition observed.

The ingredients dogs are most often allergic to are:

• beef,

• dairy,

• chicken,

• lamb,

• wheat (gluten).

Some proteins show cross-reactivity if their structures are alike, meaning that a dog allergic to chicken could have symptoms after eating turkey (but they won’t necessarily be allergic to eggs).

The vast majority of cases involve proteins of animal origin, gluten (a wheat protein) allergies are very rare in dogs, less than 10%.

How to recognise if your dog has a food allergy?

Food-allergic dogs may start with very mild symptoms that go either unrecognised or attributed to something else for a while. At some point, either because the concentration of antibodies has gotten high enough or a combination with other factors (stress, other illness, etc) they might have a severe reaction and end up at the vet.

An allergic flare-up usually starts with an itch that can become very severe as the time passes.

Later you might see:

• skin redness, pimples, weepy or crusty areas,

• an oily coat and dandruff,

• patches of thinning coat or even complete baldness,

• thickening and darkening of the skin.

Some dogs also get:

• sore and irritated paws, with lumps between their toes,

• frequent ear infections.

Sometimes they can also get other forms of allergic reactions like hives.

Approximately 20-30% of dogs with food allergies have gastrointestinal symptoms like:

• vomiting and diarrhoea or irregular bowel movements,

• flatulence.

When to see your vet

If you suspect your dog may have a food allergy, it’s recommended to speak to a vet as soon as possible.

Allergies of any kind do not go away by themselves. The produced antibodies can vary in concentrations giving milder or worse symptoms (allergic flare-ups). But overall these flare-ups only tend to get worse and happen at shorter and shorter intervals if nothing is done to control them.

What will the vet do? Diagnosis and treatment of food allergies

If your dog has bad skin symptoms, your vet will start with medication to treat these first, for example:

• antipruritics to reduce the itching (rarely steroids as these don’t work that well for food allergy-related itching),

• medicated shampoos or antibiotics to control secondary infections,

• anti-inflammatories to help with the skin irritation.

A thorough medical history of your dog will be taken to determine if a food allergy is their most likely allergy type (30% of dogs with a food allergy are atopic as well). This will be more likely if your pet:

• has an effective external parasites control, especially against fleas, so flea allergy dermatitis can be ruled out

• shows symptoms that don’t vary at different times of the year,

• develops frequent gastrointestinal symptoms as well.

Blood tests for food allergies measuring antibodies against food proteins exist, but they have been found unreliable and are rarely used in practice. Same goes for the intradermal testing.

The most reliable way to diagnose food allergies in dogs is to do an elimination diet food trial and find what they are and are not allergic to.

Food allergies are not the easiest to diagnose, but they are the easiest allergies to manage - it’s much simpler to control what your dog eats than what they come in contact with (like pollen or fleas).

Unfortunately, there is no treatment for food allergies yet, no way to teach gut immunity not to react to harmless foods. For unclear reasons, the itchiness caused by food allergies doesn’t respond very well to medication, as is the case of atopy. Finding foods that the dog is not allergic to and feeding them exclusively is the only possible way of preventing flare-ups.

How can you help your dog with a food allergy?

Feed your allergic dog only safe foods and treats that you know do not trigger allergic flare-ups. Dogs obviously don't know which foods are not ok for them, so supervise closely what your dog eats and keep a diary of your pet’s foods, treats and symptoms so that you can share this information with your vet.

Occasional flare-ups may still happen - a well-intended stranger will feed your dog a treat in the park or they may eat something scavenged. Note the places where symptoms start first (some dogs will have red ears first, some itchy paws) so you can spot a flare-up early on.

Always speak to your vet or vet nurse when you are introducing new brands of foods or treats to your allergic dog. Pet food sold as ‘hypoallergenic’ is not always hydrolysed food, and most often refers to a novel protein or a limited ingredients type of food. Check the package carefully for the word ‘hydrolysed’, either on the front or in the list of ingredients. As mentioned above, gluten or grain-free diets are rarely useful for dogs with food allergies since this allergen has a very small importance for dog food allergies.

Keep a soothing, skin barrier supporting shampoo in your first-aid kit that you can use to calm their itchiness.

Last but not least, use the button on this page to give us a call whenever you have any questions about your food-allergic dog. Our vets will be happy to help you with any necessary advice and further insights!