Mange

Mange
Classification and external resources
Dog with skin irritation and hair loss caused by mange
DiseasesDB	33039
eMedicine	article/1203895
MeSH	D008924

Mange ( /ˈmeɪnʒ/) is the common name for a class of persistent contagious skin diseases caused by parasitic mites.^[1] Since mites also infect plants, birds, and reptiles, the term "mange," suggesting poor condition of the hairy coat due to the infection, is sometimes reserved only for pathological mite-infestation of non-human mammals. Thus, mange is a term used to describe mite-associated skin disease in domestic animals (cats and dogs), in livestock (such as sheep scab), and in wild animals (for example, coyotes, cougars, and bears).^[2][3] Since mites belong to the arachnid subclass Acari (also called Acarina), another term used to describe mite infestation is acariasis.

Mammalian parasitic mites that cause mange embed themselves either in skin or hair follicles, depending upon their genus. Sarcoptes spp. burrow into skin, while Demodex spp. live in follicles.

In humans, these two types of mite infections, which would otherwise be known as "mange" in furry mammals, are instead known (respectively) as scabies and demodicosis. However, the mites that cause these diseases in humans are closely related to those that cause the mange in other mammals.

Types of mange

Two types of pet-associated mites afflict dogs and cats with a type of hair-losing dermatitis, and each type has characteristic symptoms.

Demodectic mange in dogs

Main article: Demodicosis

A dog with severe demodectic mange

Also called demodicosis or Red Mange, demodectic mange is caused by a sensitivity to and overpopulation of Demodex canis if the animal's immune system is unable to keep the mites under control. There are two types of demodectic mange: localized and generalized. Localized consists of 4 spots or less. Most dogs are immune to demodectic mange, however dogs with compromised immune systems and the elderly are at a higher risk. It is not contagious to humans.

A type of demodetic infection in humans in known, but is less commonly symptomatic. See Demodex folliculorum.

Sarcoptic mange

A street dog in Bali, Indonesia, suffers from sarcoptic mange

Sarcoptes scabiei

Puppy with Sarcoptic mange

Also known as canine scabies, sarcoptic mange is a highly contagious infestation of Sarcoptes scabiei canis, a burrowing mite. The canine sarcoptic mite can also infest cats, pigs, horses, sheep and various other species. The human analog of burrowing mite infection, due to a closely related species, is called scabies (the "seven year itch").

All these burrowing mites are in the family Sarcoptidae. They dig into and through the skin, causing intense itching from an allergic reaction to the mite, and crusting that can quickly become infected. Hair loss and crusting frequently appear first on elbows and ears. Skin damage can occur from the dog's intense scratching and biting. Secondary skin infection is also common. Dogs with chronic sarcoptic mange are often in poor condition, and in both animals and humans immune suppression from starvation or any other disease causes this type of mange to develop into a highly crusted form in which the burde of mites is far higher than in healthy specimens.

Treatment

Dogs affected with demodectic mange do not need to be isolated from other dogs. Demodectic mange is generally only contagious from mother to pup during suckling. Demodectic mange is not contagious after weaning. Many puppies will grow out of demodectic mange as their immune systems mature. Demodectic mange can recur if the immune system is compromised such as after steroid treatment or other immune-compromising illness. Treatment with ivermectin is often prescribed by vets along with skin scrapings. Ivermectin is often continued until two negative skin scrapings are achieved.

In cases of sarcoptic mange, affected dogs need to be isolated from other dogs and their bedding, and places they have occupied must be thoroughly cleaned. Other dogs in contact with a diagnosed case should be evaluated and treated.

There are a number of parasitical treatments useful in treating canine scabies. Sulfurated lime rinses applied weekly or bi-weekly are effective (warning: the concentrated form for use on plants as a fungicide must be diluted 1:16 or 1:32 for use on animal skin). Selamectin is licensed for treatment by veterinary prescription in several countries; it is applied as a drip-on directly to the skin. Ivermectin is effective and can be given by mouth for two to four weekly treatments; this drug is not safe to use on some collie-like herding dogs, however, due to possible homozygous MDR1 (P-glycoprotein) mutations that increase its toxicity. Ivermectin injections are also effective and given in either weekly or every two weeks in one to four doses. Topical 0.01% ivermectin (Acarexx) has been reported to be effective in humans and many types of animals (especially in ear mite infections where the animal cannot lick the treated area), and is so poorly absorbed that systemic toxicity is less likely in these sites. Nevertheless, topical ivermectin has not been well enough tested to be approved for this use in dogs, and is theoretically much more dangerous in zones where the animal can potentially lick the treated area.

Similar treatments are used in cats with mange, but permethrin, which can be used in both dogs and humans with this condition, cannot be used in cats. The differences in cat and dog treatment are not due to differences in the mites so much as the mitocides which are poisonous to the host.

For treatment of sarcoptic infection in humans, see scabies. For demodetic infection in humans, which is not as severe as it is in animals with thicker coats (such as dogs), see Demodex folliculorum.

Diagnosis

Veterinarians usually attempt diagnosis with skin scrapings from multiple areas, which are then examined under a microscope for mites. Sarcoptes, because they may be present in relatively low numbers, and because they are often removed by dogs chewing at themselves, may be difficult to demonstrate. As a result, diagnosis in Sarcoptic mange is often based on symptoms rather than actual confirmation of the presence of mites. A common and simple way of determining if a dog has mange is if it displays what is called a "Pedal-Pinna reflex", which is when the dog moves one of its hind legs in a scratching motion as the ear is being manipulated and scratched gently by the examiner; because the mites proliferate on the ear margins in nearly all cases at some point, this method works over 95% of the time.^[4] It is helpful in cases where all symptoms of mange are present but no mites are observed with a microscope. In some countries, a serologic test is available that may be useful in diagnosis.

See also

• Cheyletiellosis A genus of mite that causes dermatitis and itching in many groups of mammals, including pets and humans, but rarely causes hair loss, and therefore is not usually considered clinically to cause "mange"

References

1. ^ "Mange – Definition and More from the Free Merriam-Webster Dictionary". Merriam-webster.com. 2010-08-13. http://www.merriam-webster.com/dictionary/Mange. Retrieved 2010-11-14. 
2. ^ "mange" at Dorland's Medical Dictionary
3. ^ [1] Severe mite-caused mange in wild bears
4. ^ "Sarcoptic Mites and Mange: Also Known As Scabies in Dogs and Cats". Thepetcenter.com. http://www.thepetcenter.com/exa/mites.html. Retrieved 2010-11-14. 

Further reading

• Feline mange
• Red Mange (Demodicosis) on Veterinary Partner
• Demodectic mange in cats on Veterinary Partner
• Sarcoptic Mange on Veterinary Partner
• Sarcoptic Mange in the Pet Health Library
• Mange in Red Foxes (Wildlife Online)
• Bornstein, Set; Mörner, Torsten; Samuel, William M. (2001). "Sarcoptes scabiei and Sarcoptic Mange". In Samuel, William M.; Pybus, Margo J.; Kocan, A. Alan. Parasitic Diseases of Wild Mammals. pp. 107–19. ISBN 978-0-8138-2978-4. http://books.google.com/books?id=mzOaXzmAytAC&pg=PA107.