Signs your dog has allergies (and what to do about it)

Your dog has been scratching non-stop, chewing their paws like they’re made of bacon, and their ears smell like something died in them. Sound familiar? Allergies in dogs are incredibly common, affecting an estimated 10-15% of the canine population according to veterinary dermatology research. Yet many owners spend months assuming the problem is fleas, dry skin, or “just one of those things” before getting a proper diagnosis.

The thing about dog allergies is that they rarely look like human allergies. Forget sneezing and watery eyes. In dogs, allergies show up primarily through the skin, and the symptoms can be maddeningly vague. Here’s what to look for and what to do when you spot it.

The most common signs of allergies in dogs

Excessive scratching is the most obvious sign, but it’s far from the only one. Dogs with allergies might lick their paws constantly, leaving them stained a rusty-brown colour from the saliva. They might rub their face on carpets, furniture, or your freshly washed bedding. Their ears might be red, waxy, and prone to recurrent infections. Their belly might be pink or red, particularly in the groin area and armpits.

Recurrent ear infections are a huge red flag that many owners don’t connect to allergies. If your dog gets more than one or two ear infections per year, there’s a good chance an underlying allergy is driving them. Treating the infection without addressing the allergy is like mopping the floor while the tap is still running.

Other signs include hair loss (particularly around the eyes, paws, and flanks), hot spots (moist, red, inflamed patches that appear suddenly), scooting or licking the rear end, and chronic digestive issues like soft stools, vomiting, or excessive gas. Some dogs show just one symptom; others have the full collection. Poppy spent an entire spring rubbing her face on the carpet like she was trying to start a fire, and it turned out she was reacting to tree pollen drifting in through the windows.

Environmental allergies

Environmental allergies (atopic dermatitis) are the most common type in dogs. The triggers are the same things that bother allergic humans: pollen, dust mites, mould spores, and grass. The difference is how the reaction manifests. In dogs, the immune system overreacts to these harmless substances primarily through the skin rather than the respiratory system.

Seasonal patterns are a strong clue. If your dog’s itching gets noticeably worse in spring and summer when pollen counts are high, environmental allergies are very likely the cause. Dogs that itch year-round without seasonal variation may be reacting to indoor allergens like dust mites, which are present regardless of the weather.

Breeds like the Lhasa Apso, West Highland White Terrier, Boxer, and Golden Retriever are genetically predisposed to atopic dermatitis, but any breed can be affected. Symptoms typically first appear between one and three years of age.

Food allergies

True food allergies in dogs are less common than environmental allergies, accounting for roughly 10-15% of all allergy cases. The most common culprits are proteins: beef, dairy, chicken, wheat, and soy top the list. Contrary to the grain-free marketing trend, grains are rarely the problem. It’s almost always a specific protein source that triggers the immune response.

Food allergy symptoms overlap heavily with environmental allergy symptoms, which makes diagnosis tricky. The key difference is that food allergies don’t follow seasonal patterns. If your dog itches consistently all year regardless of the season, and ear infections are a recurring theme, a food allergy is worth investigating.

The only reliable way to diagnose a food allergy is an elimination diet. This means feeding your dog a single novel protein (something they’ve never eaten before, like venison or duck) or a veterinary hydrolysed protein diet for eight to twelve weeks, then reintroducing foods one at a time to identify the trigger. Blood tests and saliva tests marketed for food allergies are widely considered unreliable by veterinary dermatologists.

Flea allergy dermatitis

Some dogs develop an allergic reaction to flea saliva, and a single bite can trigger days of intense itching. This is flea allergy dermatitis (FAD), and it’s one of the most common allergic conditions in dogs worldwide. The irritation typically concentrates on the lower back, tail base, and hind legs.

The frustrating thing about FAD is that you might never see a flea. A dog with FAD grooms obsessively and often removes the evidence before you notice. If your dog has itching focused on their back end and you’re not seeing fleas, try a flea comb on the back and tail area. Black specks that turn reddish-brown when wet (flea dirt) confirm their presence.

Year-round flea prevention is non-negotiable for dogs with FAD. All pets in the household need treating, and the home environment needs attention too, since flea eggs and larvae live in carpets, furniture, and bedding. Your vet can recommend the most effective prevention for your specific situation.

When to see the vet

Don’t wait until your dog has scratched themselves raw. If you’re noticing persistent scratching, recurring ear infections, paw licking, or any of the signs mentioned above, book a vet appointment. The earlier allergies are addressed, the easier they are to manage and the less secondary damage (infections, skin thickening, scarring) accumulates.

Your vet will take a thorough history of symptoms, examine your dog’s skin, and likely check for parasites and infections first. They may recommend allergy testing, dietary trials, or referral to a veterinary dermatologist for complex cases. Don’t be disheartened if the first treatment doesn’t crack it. Allergies are a process of elimination (literally), and finding the right management plan takes time.

Managing allergies day to day

While you’re working with your vet on a diagnosis and treatment plan, there are practical things you can do at home to reduce your dog’s discomfort. Wiping paws and belly after walks removes pollen and grass allergens. Regular bathing with a gentle, oatmeal-based or medicated shampoo soothes irritated skin. Washing your dog’s bedding weekly in hot water kills dust mites.

Omega-3 fatty acid supplements support skin barrier function and have mild anti-inflammatory effects. They’re not a cure, but they complement other treatments well. A high-quality diet with good protein sources supports skin health from the inside out.

Keep your dog’s nails short. Long nails cause more damage when they scratch, turning mild irritation into broken skin and secondary infections. And try to discourage obsessive licking and chewing, though that’s easier said than done when your dog is genuinely itchy. Distraction with puzzle toys and activities can help redirect the behaviour.

The long game

Allergies in dogs are typically a lifelong management situation rather than something that gets cured. That sounds daunting, but the reality is that most allergic dogs live perfectly comfortable, happy lives once the right treatment plan is in place. Modern medications like Apoquel and Cytopoint have transformed allergy management for dogs, offering effective itch relief with fewer side effects than the steroids that were once the only option.

The key is working with your vet, being patient with the diagnostic process, and staying consistent with the management plan once you’ve found what works. Your dog is relying on you to connect the dots, because all they know is that they itch and they can’t make it stop.

Is your dog an allergy sufferer? What’s worked for them? Share your tips and experiences in the comments to help other owners in the same boat.