10 Allergy Symptoms to Look out For in Your Dog

Written by Anna Hollisey

UpdatedJan 20, 2024

Doggo having a really good scratch in the grass

From dermatitis to paw-licking, the symptoms of allergies are wide-ranging (and sometimes unexpected). Learn more about the symptoms which could indicate an underlying allergy in your dog…

First, Let’s Talk Allergies…

Before we get into the top allergy symptoms, here’s a quick look at the key types of allergies that can affect our dogs.

What causes allergies? Basically, an allergy is an overreaction to a foreign object (known as the allergen). Your dog’s immune system goes into overdrive to eliminate that allergen – which could be dust mites, pollen, fleas, or food – and that’s what causes symptoms like scratching and runny noses.

But scratching isn’t the only sign that your dog has an allergy. In fact, allergies can cause quite a surprising range of symptoms – from atopic dermatitis (itchy skin)/learn/dog-health/supplements-and-home-remedies-for-dogs-with-itchy-skin to recurring diarrhoea or ear infections.

#1 Itchy Skin (Allergic Dermatitis)

An allergen attacks your dog’s body. Right away, their immune system goes on high alert. It starts producing antibodies to fight the rogue allergen, generates extra tears and mucus, and gives your dog the urge to scratch.

But itchy skin can be extremely uncomfortable. The more they scratch, the redder their skin becomes; it gets inflamed and, if broken, can also become infected.

Allergic dermatitis is one of the most common symptoms of an allergy. If you suspect that it’s being caused by an allergic reaction, ask your vet for help diagnosing the cause so that you can tackle the problem at its root.

#2 Red or Watery Eyes

Epiphora is when tears are not properly drained back into the sinuses, which is caused by overproduction or a blockage in the tear duct. It’s characterised by staining beneath the eye (and associated infections), and it can be a symptom of an allergy (among other things).

If it is caused by an allergy, chances are that it’s an environmental one. Just like humans, the doggy immune system triggers extra tears to sweep allergens (like pollen or dust mites) out of the eyes.

#3 Ear Infections

Itchy ears can be caused by a food allergy/learn/dog-food/how-do-i-tell-if-my-dog-is-allergic-to-their-food. If your dog is sensitive to a certain ingredient, they could experience an itch which starts in their ears. Excessive scratching introduces bacteria to the ears, which causes infection.

So if your dog suffers with recurring ear infections, it’s worth considering the possibility that there is an underlying cause.

#4 Vomiting and Diarrhoea

Vomiting and diarrhoea are also common symptoms of a food allergy. If your dog gets them intermittently, it’s a good idea to keep a diary of their food intake and see whether there is any pattern.

The most common food allergens are dairy, beef, chicken, eggs, soy, and gluten. If you suspect that your dog has a food allergy, your vet might advise putting them on a restrictive diet which eliminates all six for at least 12 weeks.

Persistent vomiting and diarrhoea – particularly if it lasts for longer than 48 hours – should always be investigated by a vet, because these can also be symptoms of new and serious conditions.

#5 Swellings around the Face

Facial swelling (angioneurotic edema) can look very severe – it’s seen in dogs as well as humans, usually quite soon after encountering an allergen. Eyelids or ear flaps are most commonly affected.

Head to your vet, who can administer a fast-acting antihistamine injection.

#6 Itchy Paws

It seems strange, but itchy paws can be a sign that your dog has a food allergy. Why? It’s just one of the ways that their immune system will attempt to fight off the allergen.

Licking and chewing paws can produce hotspots, broken skin, and infections/learn/dog-health/hot-spots-on-dogs-causes-and-treatments, so it’s wise to get it treated: visit your vet for advice. An antihistamine is often recommended to treat the itchiness caused by allergies. (Before you start giving your dog Claritin or Benadryl/learn/dog-health/can-you-give-claritin-to-dogs-with-allergies, always consult the vet.)

Long-term, you can work to identify the food allergen by eliminating certain foods from your dog’s diet/learn/dog-food/5-foods-you-should-always-avoid-if-your-dog-has-allergies (and reintroducing them one at a time).

#7 Anaphylactic Shock

Very rare in dogs, like humans, anaphylactic shock is a very severe reaction which occurs soon after exposure.

#8 Hives

Hives are different to dermatitis because they appear soon after exposure and they look like lots of red raised spots – like a rash. They’re easy to miss unless your dog has very short hair; if your dog is scratching, run your hand over the area to check for bumps.

Hives are treated with antihistamines.

#9 Inflamed Skin or Hotspots

This is slightly different to atopic dermatitis (which tends to be widely-spread). If your dog suffers inflammation in one place, or hotspots, these could be caused by flea bites.

Flea allergy dermatitis is caused when a dog is allergic to flea saliva, and will excessively scratch any points of contact.

#10 Sneezing

A sneezing dog is an entertaining sight – but not when it starts to become a nuisance for them!

Sneezing suggests that your dog has inhaled a foreign body. If they’re allergic to that intruder, they’ll continue to be irritated long after they’ve blown it out of their nose! So persistent, occasional sneezing is often caused by an airborne allergen like pollen or dust mites.

Sneezing – or a runny nose – is an annoying but common allergic response and can be treated with an antihistamine. (If you have some in the bathroom cabinet, read our information about giving Claritin or Benadryl to dogs). It’s always worth trying to learn which allergen has triggered your dog.

As any person with an allergy will tell you: even the mildest symptoms can be really annoying! So if your dog could be allergic to grass, pollen/learn/dog-training/can-dogs-have-seasonal-allergies, or dust mites, monitor their symptoms and take preventative steps to save them from suffering.