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Itchy Dogs

Pet Column for the week of December 22, 1997

Related information:

Services - Dermatology

Office of Public Engagement
2001 S. Lincoln Ave.
Urbana, Illinois 61802
Phone: 217/333-2907
By Theresa A. Fuess, Ph.D.
Information Specialist

"Over 75 percent of my cases are dogs that scratch excessively," says Dr. Kinga Gortel, veterinarian and former dermatology resident at the University of Illinois Veterinary Medicine Teaching Hospital at Urbana. "These dogs may have an itchy rash, they may have hair loss from scratching, or they may just scratch incessantly. We see more itchy dogs than itchy animals of any other species, including cats and horses."

There are many conditions that cause dogs to scratch. "The three biggest ones are
parasites, allergies, and skin infections," explains Dr. Gortel.

The most common parasite that will make a dog scratch is the flea. Even with the current
excellent flea preventatives on the market, a lot of dogs suffer from fleas because owners
don't use the products. Correctly applied treatment, such as a once-a-month topical
application, is a simple and effective way to protect dogs from fleas. Even indoor dogs
should be treated because they can pick up fleas in the backyard or in parks. Mites are also
parasites that cause dogs to scratch. Parasites can cause an itch so intense that large areas
of hair are lost from scratching.

Allergies are another frequent cause of scratching in dogs. Fleas are again the most
common culprit in many parts of the country. Most dogs with fleas will scratch to some
extent, but a dog with flea allergy is miserable after only one flea bite. The next most
common allergies are environmental-due to seasonal pollens, molds, and insects-and
non-seasonal allergens, such as house dust and house dust mites. Environmental allergies
are similar to those people have. However, people usually sneeze and get a running nose
and eyes, and dogs usually itch. Food allergies, caused by one or more ingredients in the
dog's diet, are less common but can be more severe.

"The symptoms of environmental allergies can be treated with anti-inflammatories and
shampoos. However, we recommend allergy testing and hyposensitization because they are
the only real way to address the underlying disease," explains Dr. Gortel. "Most allergens
can't be avoided because they are airborne and are everywhere."

Intradermal skin testing is the most accurate method of identifying a dog's sensitivity to
allergens. Minute amounts of different allergens are injected into the skin, each in a different
site, and the skin is watched for a reaction after 15 and 30 minutes. "Skin testing is not
difficult, but experience is needed to read the reactions correctly," says Dr. Gortel. "The
animal has to be off certain medications, such as steroids and anti-histamines, to have an
accurate test." Blood tests can also be used to identify allergens.

Once the allergen is identified, it can be avoided, if possible, or the dog can be
hyposensitized. Hyposensitization is accomplished by giving the dog frequent exposures to
increasing amounts of the allergen by skin injection. The immune system then "relearns" that
these things are harmless.

Bacterial and yeast skin infections are the third major cause of scratching in dogs. Such
infections usually occur when the skin's immune system is compromised by stress, illness, or
allergies. The offending bacteria or yeast is often an organism that is normally found on the
skin but has grown beyond its usual low numbers. Bacterial infections may look like small
bumps on the skin. Yeast skin infections may be smelly and greasy as well as itchy. These
infections are easily cleared but the primary stress or illness must be treated.

"Often scratching is due to combinations of these three causes, and it is important to
address and treat each one separately," says Dr. Gortel. "Dogs don't have to be tormented
by constant itching."

For more information on pet care, contact your local veterinarian.