Itching and Allergy in Dogs

Date Published: 07/09/2007
Date Reviewed/Revised: 04/01/2020
Certain shampoos can ease itching. Photo courtesy of Depositphotos

Coping with an itchy pet can be an extremely frustrating experience for a pet owner and can truly test the limits of the human-animal bond. Persistent scratching and chewing by a dog can also result in open wounds to the skin and pain to your pet. The following information is intended to help provide pet owners with a basic understanding of the most common underlying causes of itching and allergies in small animals. Here’s a summary of the most common underlying causes of itching and allergies in small animals.

What are the most common causes of chronic itching?

Itching in dogs can involve not only scratching but also chewing, licking, and rubbing. The two most common causes of itching are external parasites and allergies. Examples of itchy external parasites on dogs are fleas and small bugs called sarcoptic mange mites.

What are the major types of allergies in dogs?

Allergies are a common cause of skin and ear conditions in dogs. People with allergies usually have “hay fever” (watery eyes, runny nose and sneezing) or asthma. However, dogs with allergies rarely have respiratory signs from their allergies and instead usually have red and itchy skin, hair loss, or recurring skin or ear infections.

What are the major types of allergies in dogs?

Flea allergy
Flea allergic dermatitis is the most common skin disease in dogs. For the flea allergic patient, 100% flea control is essential for remaining symptom-free.

“But doctor, I never see fleas on my pet.” You may not see them, but that doesn’t mean they aren’t there! Flea allergy is caused by the flea’s saliva, and it only takes a few bites to cause a problem. Also, an itchy dog often scratches so much that adult fleas are hard to find because they are removed from the body.

“If fleas are the problem, why is my pet still itchy in the winter?” In warm climates or in our homes, fleas may survive in low numbers year-round. Because flea allergy is so common, many veterinarians recommend instituting complete flea control before proceeding with tests for itching. For most allergic dogs, year-round flea treatment is an important part of reducing itch.

Food allergy
Some pets develop hypersensitivities to foods. Various food proteins, carbohydrates, or even preservatives or dyes can all be potential food allergens. There is currently no accurate blood or skin test to determine if your dog has a food allergy. The only method of diagnosing a food allergy is by placing your dog on a carefully selected prescription or homemade hypoallergenic diet for several weeks, which is called a food trial. The diet only contains ingredients your dog has never eaten before. If the allergy signs resolve, a food challenge is performed by feeding the former diet and watching for a return of the itching. If this occurs, a diagnosis of food allergy is confirmed.

Atopic dermatitis
Atopic dermatitis is a type of allergy. Skin or ear inflammation occurs in response to a variety of normally harmless substances, such as plant pollens, house dust mites, and other environmental allergens. Allergy tests of the skin or blood help us compile a list of allergens for a “vaccine” (allergen specific immunotherapy) to decrease the pet’s sensitivity.

Secondary infections
Allergies are often the underlying cause of recurring skin and/or ear infections. Bacterial and yeast infections, though secondary to the allergy, can increase your pet’s level of itching. Long-term treatment with antibiotics and anti-yeast medications is commonly required, along with medicated bathing programs.

Can allergies be cured?

Unfortunately, there is no cure for allergy and it is usually a life-long problem. We seek to control allergies and improve the quality of life for both you and your dog. We will formulate the best program of management that suits all involved with your dog’s care.

Can the itching be treated without the expense of diagnostic testing?

There are many anti-allergy medications to reduce itching. These medications do not cure allergies but can help decrease the symptoms. However without addressing the underlying cause of the allergy, the itching will return when the medication is stopped. Long-term use of some anti-allergy medications, such as steroids, can result in many health problems. Working with your veterinarian to diagnose the underlying cause of the allergy and itching may reduce the need for medications or enable your veterinarian to use more specific and targeted allergy treatments.

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