Pet Talk: The mangy dog is not what you think
February 23, 2012
Since our holiday puppies are now around four to six months old, I thought I’d write about one of the more common puppy problems, Demodectic mange. Demodectic mange is one of those difficult to understand and explain diseases. The word mange conjures up images of unkempt, dirty, malnourished animals, yet this is often not the case with demodectic mange. A very common comment when told of the diagnosis is “but I take such good care of her; how could this happen?”
Relax. You have. What you are probably thinking about is Sarcoptic mange, or Scabies. The two diseases are vastly different.
Demodectic mange or demodex, is caused by the mites of the demodex species. It differs from Scabies or sarcoptic mange in a number of ways. First, it is not contagious to either dogs or to humans like scabies is. This is a tough concept to swallow for many of us; how can a skin condition that looks so bad not be contagious? Trust me it isn’t. I had one young lady ask me “well, how do you know?”
“I went to school for eight years and I know how to read medical texts and journals,” I assured her. More than once I have copied articles for my clients. I’ll repeat again. It is not contagious
Demodicosis causes hair loss, skin thickening, oozing sores, skin infections, red, irritated skin, and is usually very itchy. There are two forms of the disease, both caused by the same mite. One is called localized demodicosis; the other is generalized demodicosis. Again, this is a difficult concept to grasp; two different diseases caused by the same organism.
Localized demodicoses involves a few patches of hair loss, usually around the head, neck and hocks. It usually occurs in puppies around six to eight months old and often resolves without treatment. It is not a very serious disease. When the demodex begins to spread uncontrollably we call it “generalized,” as larger areas of the body are involved. This is a much more serious disease and requires aggressive therapy.
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There is a lot we do not know about demodectic mange. Most agree it has an underlying immune system dysfunction involved with it. The most popular theory is that affected dogs have a inherited, cell-mediated immunodeficiency. Some breeds of dog (i.e.. Shepherds, Dalmatians) seem to be affected more than others, but demodex is seen in all breeds.
Diagnosis of demodex is fairly straightforward. A scalpel blade is used to scrape the top layers of skin off for examination under a microscope.
There is only one approved product to treat demodectic mange, Amitraz or mitaban. Treatment is continued two to four dips after a negative skin scraping. This averages six to eight dips. We always try to correct any underlying problems such as nutritional deficiencies, parasitic infestations or secondary skin infections. In recent years some new, off-label treatments have been discovered (these are treatments that are not FDA approved usage of these drugs). These protocols use the drugs ivermectin and milbemycin (which are the active ingredients in Heartguard and Interceptor). Some animals can be controlled with a combination of dipping and the newer protocols.
I empathize with my clients whose dogs have generalized demodicosis. The good news is that most dogs are cured and lead completely normal lives (except for breeding, which is discouraged if your dog contracts generalized demodicosis).
Veterinarian Stephen Sheldon, DVM, practices at Gypsum Animal Hospital. He can be reached at 970-524-DOGS or at the hospital website http://www.gypsumah.com.