7 Dog Allergy Symptoms to Look For

Matthew Everett Miller, DVM
By Matthew Everett Miller, DVM on May 12, 2020

Allergies are common in dogs. About 1-2% of all dogs have a food allergy, and as many as 25% of dogs with skin problems have a food allergy.

When you throw in dogs with inhalant or environmental allergens (like pollen or mold) and flea allergies, you’re looking at a sizeable portion of the canine population that’s suffering from allergies.

How can you tell if your dog has allergies?

Many diseases can cause the same symptoms as allergies in dogs, so it will be up to your veterinarian to determine for sure whether allergies are to blame, and if possible, the cause of those allergies.

Look for these signs and go to the vet to confirm whether your dog does, in fact, have allergies.

Your Dog Never Stops Scratching

One of the most common symptoms of allergies in dogs that pet parents notice is itchy skin.

The severity of the itchiness can vary from quite mild, in which case the skin and haircoat look mostly normal, all the way to nonstop scratching.

In the more severe cases, hair may be missing, and the underlying skin can appear to be red, raw, and inflamed.

Classically, the epicenters of itch include:

  • Chest

  • Armpits

  • Belly

  • Feet (especially the front feet)

  • Ears

  • Eyes

  • Mouth

  • Groin

  • Area around the anus

Importantly, itchiness of the lower back, specifically near the base of the tail, is a hallmark sign of flea allergies.

Over time, these areas may become “hyperpigmented,” or dark in color. The skin may become quite odorous and can take on a notably different texture.

Your Dog’s Feet Smell Like Corn Chips and They Won’t Stop Licking Them

While most humans think that the corn chip smell is normal for a dog’s feet, it’s actually a sign of bacteria. If your dog is also licking their feet, it’s not because they’re cleaning—their feet are itchy.

If your dog’s hair is a light color, you may notice “fur staining” of the feet, a symptom in which the fur takes on a dark red, coppery color due to the dog’s saliva.

The classic corn chip odor of the feet, which many people believe to be completely normal in dogs, is caused by skin infections, either from bacteria (usually Staph) or fungi (usually yeast). So how is this symptom related to allergies?

The inflammation associated with skin allergies breaks down the normal skin barrier over time. As a result, opportunistic microbes like yeast and bacteria can go from resting peacefully on the surface to diving deeper, where they set up infections and cause problems.

Addressing these secondary infections will be one of the first steps that your veterinarian will want to take in treating your allergic dog.

Your Dog Has Chronic Ear Infections

Relatedly, many dogs with allergies will experience ear infections that recur frequently or never seem to fully go away. As with the feet, this problem is often caused first by the allergies.

The allergies break down the healthy skin barrier, then opportunistic bacteria or yeast create an infection, which all further contributes to the itch (although ear infections unrelated to allergies are common as well).

Dogs that have gone years with allergies that are either undiagnosed or undertreated will often have ears that are raw, smelly and thickened.

In severe cases, ear infections may become so resistant to treatment that surgery to remove the ear canal may be required. To avoid this situation, it is important to have your dog examined by your veterinarian as soon as you suspect that your dog may have allergies or ear infections.

You Notice Recurring Hot Spots

Formally known as “pyotraumatic dermatitis,” hot spots are common in dogs, especially in breeds like Goldens, Labs, and Saint Bernards.

Like ear infections, hot spots can arise on their own, or they can be secondary to underlying allergies. If you feel like you’re always treating a new hot spot on your dog, talk to your veterinarian about allergies.

Your Dog Suffers From Chronic Diarrhea and Related Symptoms

You might think that the skin is the area that’s most commonly affected by allergies in dogs, but the gastrointestinal (GI) tract is just as likely to suffer when a dog’s allergies are poorly controlled.

GI-related allergy symptoms include:

  • Diarrhea

  • More frequent bowel movements

  • Straining to defecate

  • Vomiting

  • “Gurgly” gut noises

  • Gradual weight loss

  • Increased salivation

  • Passing gas

  • Abdominal discomfort

Your Dog Has Red Eyes

It’s less common for dog allergies to manifest in their eyes, but it is possible.

When certain parts of the eye become red and inflamed, especially if both eyes are affected, an allergy may be at play. The term for this condition is allergic conjunctivitis.

The redness may be accompanied by squinting or pawing at the face.  

Your Dog Is Coughing

A nonproductive cough that worsens during exercise may be yet another sign of allergies. Known as allergic bronchitis, this condition is more common and more severe in cats, but it is a possibility in a dog with allergies.

Talk With Your Veterinarian

As always, talk to your veterinarian if you suspect that your dog may have allergies. They may perform tests to rule out more common or more serious diseases that can cause similar symptoms.

To decide whether allergies are likely the culprit, your veterinarian will also take into account:

  • The age of onset (environmental allergies typically show up in a dog’s first three years of life, whereas food allergies are seen in dogs 5-7 years old)

  • Your dog’s breed

  • The seasonality of the symptoms

  • Previous and current diets

Featured Image: iStock.com/Przemysław Iciak

Matthew Everett Miller, DVM


Matthew Everett Miller, DVM


Matthew Everett Miller is a Kentucky native, veterinarian, and writer whose fiction and journalism have appeared in Slate magazine, the...

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