Allergies in Dogs: What Causes Them?

Allergies in dogs are one of the most misunderstood topics that you may come across as a dog owner.

We see opinions about which product is best for allergies in dogs, how is best to cure allergies or how to prevent allergies from happening, every single day.

Maybe you’re wondering what even is an allergy? Well, it is a misguided reaction to foreign substances by the body’s immune system.

There are a lot of allergy types in dogs – some of these include skin, food and even the environment.

Symptoms of allergies can sometimes overlap which occasionally makes it hard to determine what exactly the cause is.

golden retriever with allergies 


The most common causes for skin allergies are fleas, food and the environment.

Some dogs are allergic to fleas. You’ll notice them with an itch that they just can’t scratch – especially in their tail – or with red patches around their body. If your dog has fleas, you may even be able to physically see them on your dog as well as the symptoms that are present.

Food allergies or food sensitivities will also cause your dog to itch. The best way to know if it’s a food allergy that your dog is experiencing is to check if they are itching their ears and paws more than another part of their body. It will often be paired with gastrointestinal symptoms if food is the cause.

Environmental allergies include dust, pollen and mold. This kind of allergy causes atopic reactions in a dog, otherwise known as atopic dermatitis or hotspots.

Skin allergies pose a risk of secondary infection if not treated.


It is important to know that there’s a difference between food allergies in dogs and having a food sensitivity. 

Food allergies cause reactions such as hives, swelling, itching, vomiting and diarrhea. These are all immune system responses and can result in anaphylaxis which needs to be treated as soon as possible after the event.

Food sensitivities are not immune system responses but rather gradual reactions to offending ingredients. A dog that is sensitive to a particular food will often show gastrointestinal signs and symptoms, dermatologic signs, chronic ear or foot infections and in some cases, vomiting and diarrhoea.

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Signs and symptoms of allergies in dogs may vary from dog to dog. They may also be signs of other diseases so it is important to always check with your vet before making a diagnosis yourself.

Common symptoms of allergies include:

- Itching, (this can be anywhere on the body but in particular paws and ears are the most common sites)

- Ear infections

- Hives

- Swelling, (this includes the face, eyes, lips and flaps of ears)

- Red, inflamed skin

- Diarrhoea

- Vomiting

- Sneezing

- Itchy, runny eyes

- Licking


It is complicated to diagnose an allergy or sensitivity, particularly if it is food related. Allergy tests such as the elimination diet are popular amongst many. This includes eliminating foods from your dog’s diet for 12 weeks. It usually means feeding one protein source and one carbohydrate source in a meal to get a clear idea of whichever may be the problem. 

Flea allergies are the easiest to diagnose.

boston terrier dog with allergies


Treatment for dog allergies vary depending on which allergy they are experiencing.

It is important to keep your dog’s immune system optimal in order for it to fight allergies. You can help to boost the immune system with dog supplements.

Probiotics or supplements high in omega 3 work to protect your dog’s natural allergen barrier and keep their gut balanced. Omega 3 in particular can help to reduce inflammation associated with allergies and have an alleviating effect on an over-reactive immune system.


Flea-related allergies will require flea treatment. There are many different types out there so if you’re stuck for which one is right for your dog then it’s always best to consult with your vet.

Food sensitivities as mentioned above are often discovered with elimination diets. To treat a food sensitivity, it needs to simply be discovered and removed from your dog’s diet. You may need to consider a total diet change or a partial diet change depending on the allergy or sensitivity. It is helpful to know that carbohydrates can trigger or worsen inflammation in your dog’s gut.

Another way to treat allergies in your dog is to simply avoid the allergen. Environmental allergies such as particular types of grass can be avoided by switching the park which you walk in each day. Food allergies can be avoided if you do not include them in your dog’s meals.

Breeds that allergies are common in include but are not limited to: Terrier, Setters, Retrievers, Pugs, Bulldogs and Boston Terriers.


Remember that signs and symptoms of allergies that you can see are a result of something deeper. Finding the root cause and addressing it is the key to a more comfortable life for your dog.