by Barry B. Burtis D.V.M.
Our pets can sometimes be very adept at hiding or masking their signs of illness. Sometimes even the most astute and observant owner feels guilty for not recognizing sooner that their pet was not well. However, when changes occur in a pet's haircoat, it usually is able to be detected easily. That's particularly true when the pet's hair goes missing. In the last column, missing hair or alopecia was discussed and this time that discussion will continue.
A veterinarian being consulted about a pet's alopecia quickly wants to know whether the pet is showing signs of itchiness as well as hair loss. If the pet is itchy, there's a good chance the hair is gone because the pet is breaking or chewing it off. There are not a whole lot of things that will make a pet so itchy it will do this. Some of the skin parasites certainly can. Infection with Sarcoptes, Demodex, Chyletiella and Notoedres mites, called the mange mites in cats and dogs, can produce hair loss. Ear mites occasionally make a cat scratch so much that they develop areas of hair loss behind their ears. Fleas make a pet itchy, but usually not enough to create bare skin areas, unless the pet is also allergic to the flea. Flea allergy dermatitis, caused by an allergic reaction to the flea saliva, injected into the pet when it is bitten, is very common. When the warm weather arrives, it's important to remember to get your pet started on a flea preventive. It's the one kind of allergy that we can now protect against. After flea allergy dermatitis, skin allergies, reactions to things a pet contacts, things a pet eats or things a pet breathes in the air, are probably the most common reason for a pet to become itchy enough to cause alopecia. Yeast infections of the skin also can be a cause for itchiness that leads to loss of hair.
It's another matter if a pet is developing bald areas on its body and yet seems quite oblivious to the fact. With a pet who is not itchy, uncomfortable or otherwise bothered by the loss of hair, there are a number of other diseases that will need to be considered in arriving at a diagnosis of the problem.
There are a number of hormone disorders that can cause alopecia as one of the signs in an affected dog. Cushing's disease or overactive adrenal glands, as well as an under-active thyroid or altered activity of the sex hormones can cause hair loss. Growth hormone-responsive dermatosis has been associated with an alopecia that often starts along the collar area of the neck and may progress to affect the back and sides of the body in dogs.
Hormone disorders seem to be a less common cause of alopecia for cats. In middle-aged or older cats, a partial or complete alopecia associated with self-barbering can occur with hyperthyroidism or increased thyroid activity. Neutered male cats rarely develop an alopecia along the rear aspect of their hindlimbs which is thought to be hormonal in origin.
Veterinarians rely on an accurate history of the nature of the problem from the owner, followed by a thorough general physical examination of the patient to begin to sort out the possible causes for alopecia in a pet. Often, blood tests and other diagnostic laboratory procedures will be required, as well. Occasionally a skin culture, a skin biopsy or other specialized techniques will be needed to confirm a diagnosis.
Depending on the specific cause of the alopecia, there are a number of treatment measures that may be used in the affected pet. Hopefully, when corrected, hair regrowth will occur and further hair loss prevented. Barry Burtis is a local veterinarian. Past Pet Tales can be found at www.baycitiesanimalhospital.ca