You've probably heard the term "mangy mutt" referring to a poor, broken-down dog with a ratty, patchy coat. That's actually how dogs with mange really look. Mange is a condition caused by an infestation of a specific type of mite that is too tiny to be seen with the naked eye. Its Latin name, Demodex canis, gives rise to the formal names for this condition: demodicosis or demodectic mange.
It's considered normal for healthy dogs to carry around a small population of mange mites. Newborn puppies acquire them from their mothers, and they don't generally cause any problems. The trouble starts when there's a population explosion and the mites get out of control. It can happen in puppies or adult dogs with compromised immune systems, but it usually occurs in dogs under the age of one year. There also appears to be a genetic connection. Some pure breeds can be more susceptible to demodicosis, such as bulldogs, chihuahuas, collies, German shepherds and pugs. Some vets recommend that dogs diagnosed with the more severe form of the condition be neutered so they can't pass it along. To diagnose demodicosis, your vet will gently scrape off some of the superficial layers of the dog's skin and examine them under the microscope to see if mites are present.
Demodex canis isn't the only type of mite that can cause mange. Sarcoptes scabei (var. canis), is the cause of sarcoptic mange -- better known as scabies. This mite is highly contagious and does not occur naturally in dogs. It burrows into the skin's outermost layer and lays its egg. The eggs hatch, the larvae mature and the emergent adult mites start the life cycle all over again. Scabies can be passed from dogs to people through direct contact. It is diagnosed and treated very similarly to demodectic mange, but you'll want to isolate your dog to avoid the spread of the scabies and treat all other pets in the household. In humans, scabies causes red, itchy bumps that look like mosquito bites.
Next, learn about the different types of demodicosis, how it's treated and how to prevent it.
Demodicosis can be localized, meaning that the condition is found on only one area of the dog's body, or it can be generalized, spreading over the entire body. Localized demodicosis is the most common form, and it often clears up on its own in a few months (although it can wax and wane over time). Signs include thinning hair that progresses to one-inch (2.5 centimeter), patchy hair loss, generally on the face or the front legs. The skin can become red and scaly. Generalized demodicosis has similar signs, but they're widespread and more severe. The skin can break down and become infected, with painful, draining sores. There's also a form of demodicosis called demodicoditic pododermatitis. It solely affects the dog's feet and can be very resistant to treatment.
To treat localized demodicosis, your veterinarian will likely prescribe an ointment that contains benzoyl peroxide, which you will need to massage daily into the affected areas. Generalized demodicosis requires more intensive treatment. This includes shaving the dog, using a medicated shampoo containing benzoyl peroxide to bathe him and dipping him using a miticide. The medicated shampooing and dipping will likely have to be repeated once or twice a week for up to a few months, with follow-up skin scrapings to determine if the demodicosis is gone. It's important to get your dog diagnosed properly and carefully follow the treatment plan prescribed for him rather than trying to treat demodicosis on your own. The dip can have some nasty side effects such as vomiting, diarrhea, dizziness and lethargy. If your dog has a bad reaction, rinse it off of him immediately and call your vet. Your vet may also prescribe antibiotics to clear up bacterial infections.
In about half of puppies diagnosed with localized demodicosis, the condition goes away on its own. This doesn't happen in older dogs, however, or in dogs with generalized demodicosis or demodicoditic pododermatitis. Many dogs need long-term, intensive treatment, and curing demodicosis can be difficult. To help prevent mange, regularly bath and brush your dog. Washing his bedding once he has been diagnosed will also help with the condition.
- AAHA. "Mites and Mange." Healthy Pet. 2011. (June 17, 2011) http://www.healthypet.com/PetCare/PetCareArticle.aspx?art_key=951bd0a2-a764-4710-a0e7-efd11ee92409
- ASPCA. "Mange." ASPCA. 2011. (June 17, 2011) http://www.aspca.org/pet-care/dog-care/dog-care-mange.aspx
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- Eldredge, Debra M., et al. "Dog Owner's Home Veterinary Handbook." John Wiley and Sons. 2007.
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- Nash, Holly. "Sarcoptic Mange." Doctors Foster and Smith Pet Education. 2011. (June 17, 2011) http://www.peteducation.com/article.cfm?c=2+2111&aid=764
- WebMD. "Demodectic Mange." WebMD. 2011. (June 17, 2011) http://pets.webmd.com/dogs/demodectic-mange-dogs
- WebMD. "Mange in Dogs (Canine Scabies)." WebMD. 2011. (June 17, 2011) http://pets.webmd.com/dogs/mange-dogs-canine-scabies