E372
Itching (Pruritus)

Introduction: Scratching is one of the most common reasons a dog is brought to a veterinarian. Because there are so many different things to which the skin can react, these problems are often quite challenging to diagnose.

Causative Agents: Some of the more common underlying reasons for itching in dogs are: infections (bacteria, fungus, fleas, mites, etc.), allergies (contact, inhalant, and food allergies), auto-immune skin diseases (pemphigus, lupus, etc.), and drug reactions.

Clinical Signs: Scratching in dogs may take the form of rubbing, chewing, and licking, in addition to scratching with the claws. Evidence of scratching in its various forms includes hair loss, bleeding, observing the actual scratches or bite marks, and thickened, ulcerated, red, or crusty skin. Chronic licking may result in dark brown saliva stains on dogs with light-colored hair coats.

Diagnosis: General history and physical exam are the beginning point. Some of the questions that are important in the history include the following:

  1. Is there any possible exposure to toxins and irritating substances?
  2. What is the animal’s living environment like?
  3. What is the dog’s current diet and have there been any diet changes?
  4. Is the itching worse during certain seasons?
  5. Are any other animals or people in the household affected?
  6. How intense is the itching?

Diagnostic tests which may follow the dermatologic examination include skin scrapings, impression smears, tape preparations, and cultures. These are all methods of detecting infectious agents on or in the skin which may be causing itching. Skin biopsies, response to dietary trials, and special skin or blood tests for identifying specific allergies are also used. It is not uncommon to find that a severe skin problem is actually the result of a combination of causes.

Treatment: Successful treatment of skin problems depends on a proper diagnosis. A variety of medications and therapies are used for the various skin problems encountered in dogs. Some of these include administering antibiotics, anti-inflammatory drugs (especially steroids), parasite treatments, and antihistamines. Special diets and an assortment of shampoos, rinses, topical ointments, and creams are also available. For some dogs diagnosed with allergies, hyposensitization therapy is recommended. Hyposensitization therapy requires identification of the specific things causing the reaction (specific pollens, air-borne molds, house dust, etc.). A custom-made set of injections is then obtained which help to desensitize the dog’s immune system to the items causing the reaction. Once the immune system is properly desensitized to these allergic elements, exposure to them will generally produce less of a reaction. Many itching dogs require some type of lifelong therapy to keep them comfortable.