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Greyhound with rash

Does your Greyhound sometimes have a belly rash, or red/itchy patches around the eyes, underarms, groin, muzzle or between toes? Dog allergies often present as skin irritations, marked by inflammation, excessive scratching or licking. Allergies for dogs and humans alike occur when the immune system overreacts to a perceived threat from an outside source. Although increasingly common, it can be difficult to diagnose and treat. Read on to learn more about the causes, symptoms, and management of allergies 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.

Most allergies occur in dogs over 6 months old or older. A dog that is repeatedly exposed to a particular allergen becomes sensitized to it, and the immune system overreacts to a subsequent exposure. The majority of allergies in dogs manifest on the skin, whether or not the allergen has come into direct contact with the skin. This can make it tricky to diagnose the cause of the dog skin allergy. It is important to pay close attention to the allergic reaction, especially when and where it occurs.

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.

Greyhound with rash


Exposure to the allergen, usually on multiple occasions spanning months to years, sensitizes the immune system, and a subsequent exposure to the same or related allergen causes an over-reaction. Normally the immune system protects the dog against infection and disease, but with allergies, the immune response can actually be harmful to the body. Allergies may be thought of as an unnecessary normal immune response to a benign foreign substance.

The immune reactions involved in allergies are quite complex. Most reactions involve allergen protein molecules combining with antibodies in the blood, then releasing potent chemicals, such as histamines, that cause local inflammation such as redness, swelling, and itching. This inflammation causes the various signs associated with an allergic reaction.

In dogs, the most common symptom associated with allergies is itching of the skin, either localized (in one area) or generalized (all over the body). In some cases, the symptoms involve the respiratory system, with coughing, sneezing, and/or wheezing. Sometimes, there may be runny discharge from the eyes or nose. In other cases, the allergic symptoms affect the digestive system resulting in vomiting and diarrhea.


Allergies typically become noticeable after a dog is two years old and can be caused by the following:

  • Pollen from plants, trees, and grass
  • Spores from mold
  • Dust mites and parasites
  • Feathers
  • Dander (including cat dander)
  • Smoke
  • Perfumes
  • Cleaning products
  • Fabrics
  • Rubber
  • Tick and flea preventatives or other medicines
  • Pet shampoos

Around 10% of the allergies your pet encounters may be triggered by food. Some of the most common allergens for dogs are regular meat, dairy, eggs, corn, soy, and wheat. Eliminating these and watching for others is the start to a more comfortable pup.


Skin allergies, also known as allergic dermatitis, is one of the most common types of dog allergies. These are usually caused by reactions to flea bites or their surrounding environment such as pollen, dust or mold.

Atopic dermatitis is a chronic skin condition associated with allergies in dogs. It can either be the result of an allergic reaction, or due to coming into contact with an irritant, such as a chemical, or a certain plant or animal.

Canine atopic dermatitis usually appears in younger dogs, between the ages of 3 months and 6 years. It may, however, take some time to diagnose, and can worsen with age.

Symptoms include:

  • excessive scratching
  • excessive licking
  • excessive chewing
  • skin inflammation
  • rashes
  • sneezing

Atopic dermatitis typically affects areas where the skin is thinner or more sensitive, such as the ears, around the eyes, underarms, groin, muzzle, and between the toes.

A contact allergy is caused by the dog’s skin coming into contact with a specific substance or material, such as shampoo, flea treatments, or wool bedding. This type of allergy is usually manifested on the dog’s skin in the form of itching and dermatitis. The allergic reaction will be localized to the area that came into contact with the allergen. Contact allergies are the least common form of dog allergies, but can still be very uncomfortable for your pet.

Belly rash

Contact allergies in dogs are treated by removing the allergen, and in extreme cases with antihistamines or steroids to treat the symptoms. It can sometimes be challenging to identify the allergen, especially if your dog develops an allergy to a product that you have been using for some time.

Try keeping a record of every substance that you are putting on your dog, and cross-referencing when the allergic reaction occurs. This can help you to identify the allergen and then remove it.

Hotspots on dogs, also called acute moist dermatitis, are moist, red, irritated skin lesions. The most common locations of hotspots on dogs are on the head, chest, and hips. Dogs will often lick or chew on the affected area, causing the hotspot to grow quickly. Although dogs with longer coats are more likely to develop hotspots, any dog with allergies can develop these painful sores.


Fleas or a flea bite allergy is the most common skin disease in dogs. These dog allergies are a result of a reaction to flea saliva on your dog’s skin, and symptoms will vary from mild itching to a severe reaction when bitten, most often noticeable at the base of the tail. Usually these allergies will appear when they’re young (between 1-5 years old), but they can develop at any age.

Dogs with flea allergies will usually have severely itchy skin. Itchiness is sometimes referred to by its medical term, ‘pruritus’. They may scratch, rub, chew or lick their hair or skin, and this can sometimes result in trauma to the skin or introduction of a secondary infection. Additionally, other dog allergy symptoms may be present such as hair loss and scabbing, and flea dirt may be visible on the skin or in the coat too.

Bear in mind that even if your dog is treated monthly for fleas, they could still suffer from a flea allergy! Many flea treatments will only kill the flea once it has bitten your dog, and unfortunately this single bite is often enough to trigger an allergic reaction and itching in a sensitive dog.

Despite the name, ringworm isn’t actually caused by worms, but rather by a fungal infection. Ringworm is contagious to humans and can be transferred from dogs to humans and other animals. The symptoms of ringworm in dogs are itching and patches of hair loss, usually located on the head, ears, and forelegs. This helps to differentiate it from a flea bite allergy.


An environmental allergy, seasonal allergy or inhalant allergy is caused by allergens in the air that your pet breathes in. This is also known as atopy.

Environmental dog allergies are usually caused by dust, pollen or mold. This type is usually seasonal, so it will probably only appear at certain times of the year – dogs can suffer from hay fever so you may notice sneezing or irritation when the pollen count is high. Areas around the paws, ears, lower legs, muzzle and groin are usually the most affected skin spots and your dog might have bald or sore patches from excessive itching. Sometimes, an environmental allergen can be resolved simply by ‘avoidance’ – for example, if you know you dog’s allergic symptoms appear worse on walks through particular fields with long grasses you may need to avoid this and use pavements at certain times of the year. Some owners swear by bathing their dogs more frequently during allergy season to remove allergens from the coat. Others install air purifiers in their houses to remove particles.


Contrary to popular belief, food allergies in dogs aren’t very common, and actually only make up about 10% of allergies or less in dogs. Most of what owners believe are ‘food allergies’ are actually intolerances.

An intolerance differs from an allergy: an allergy involves the immune system, so the body must have been previously exposed to the ‘allergen’ (which is usually a harmless molecule). In comparison, an intolerance does not involve the immune system and can occur the first time a dog encounters that substance. An example would be a lactose intolerance: in this case, the dog would lack the enzymes needed to digest lactose, so if given some milk he or she may suffer from diarrhea because of an inability to digest the ingredient.

Although not always the case, an allergy tends to provoke a skin reaction, such as a swelling or itchiness, more commonly than a gastrointestinal problem like vomiting and/or diarrhea, whereas an intolerance is more likely to result in gastrointestinal signs.

Dogs can develop a food allergy or food hypersensitivity at any age, and to any carbohydrate or protein component of their food. Antihistamines and steroids are usually not effective in treating a food allergy in dogs.

Instead, to identify and treat food allergies in dogs, most veterinarians recommend an elimination diet that will cut out specific ingredients, one at a time. Once you identify the allergen, you can then eliminate that specific component from your dog’s diet for good.

Your vet will advise you of the best way to carry out this diet. It is essential that you stick to the diet all the way through, even if your dog’s symptoms subside. Treats and supplements are also components of the exclusion diet.


Sometimes dog allergies can become severe and may result in anaphylactic shock. Most commonly these reactions are due to things like a bee sting or a wasp sting. Signs of anaphylactic shock can appear within minutes of exposure and may include: difficulty breathing, drooling, vomiting, seizures and sometimes even a loss of consciousness. If this does occur, you should contact your vet immediately.


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.

The classic corn chip odor of the feet 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 any secondary infections will be one of the first steps that your veterinarian will want to take in treating your allergic dog.

While there is no cure for dog allergies, by treating the symptoms and removing the allergen if possible, you can assure your hound a good quality of life in spite of allergies. Next week, we will look at the various treatments available for the different types of allergies, as well as home remedies to keep your pup more comfortable.



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