Sarcoptic mange is one of those itchy conditions where I start talking about it and find myself scratching! When people refer to a stray dog as being a “mangy animal,” they are actually referring to the thickened skin and hair loss caused by the sarcoptic mange mite.
Unlike fleas, which are large enough to be seen with the naked eye, this pesky little critter (Sarcoptes scabiei) is microscopic. Not only that, but female mites like to burrow into the skin (ouch!) and lay eggs, which then hatch in pockets off of the burrow (double ouch!).
When I mention mange as a possibility to my clients, they are often surprised because they looked through the pet’s coat and didn’t seen any bugs — but as you now know, the mites are too small to see with the naked eye.
This is a highly infectious parasite and readily passed between dogs or between wild animals such as foxes. However, the mite is not picky, and in the absence of your dog will try munching on your skin. Are you itching yet?
Dogs with a Sarcoptes burden are itchy — very itchy — and if you touch their flanks it often triggers vigorous scratching with a back leg.
Indeed, the dog may scratch so much that he damages the skin. Skin infections are a common consequence of mange. Typically the legs, the muzzle and edges of the ear are affected first. The skin becomes thickened and inflamed, and some of the hairs fall out, giving an overall “moth-eaten” appearance.
However, mange mites respect no boundaries, and as the infection spreads, any part of the dog’s coat may be affected.
Eventually most of the fur falls out, and the skin becomes thickened, dry and infected. Incidentally, if you get your nose tuned into such things, mangy skin has a distinctive “mousy” odor about it.
The cause of mange is the Sarcoptes scabiei mite. Not only does this mite’s burrowing habits cause irritation to the host but also it is one little allergen machine with antigens on the surface of the mite.
The eggs, larvae and feces are all likely to trigger an allergic reaction with — you guessed it — extreme itching.
The traditional way of diagnosing sarcoptic mange is deep skin scrapes.
This involves moistening the skin with mineral oil and then blunt-scraping the skin’s surface until it starts to ooze blood. The sample of skin cells on the scalpel blade are transferred to a slide and examined under the microscope for the presence of mites.
However, there is now a blood test available that looks for the body’s immune response to the presence of the mite. The only downside is that the pet needs to be infected for at least a couple of weeks to mount a sufficient immune response that shows up on the blood test. For a recent infection, skin scrapes are the way to go.
Fortunately, treating mange is a whole lot easier than it used to be. It is easily treated with topical applications of a spot-on product containing selamectin such as Revolution (US) or Stronghold (UK).
The oral anti-parasite treatment Milbemax (containing milbemycin) is also effective at a dose of 2mg/kg if given once a week for 6 treatments.
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Regular application of an anti-parasite product effective against Sarcoptes, such as Revolution, is effective at preventing infection.
- “Sarcoptes scabiei and scabies.” Burgess. Advances in Parasitology, 33: 273–292.
This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Oct. 13, 2018.