An explanation of the various types of mange in dogs and cats--all caused by mites--their degree of seriousness, treatment, and prevention.
Mange is a catch-all term for various skin conditions that include scabies or sarcoptic mange in dogs (known as notoedric mange in cats), demodectic or "red" mange, cheyletiella mange, and ear mite infections. They are each caused by a different mite.
Sarcoptic mange afflicts dogs, cats, and other animals, including humans. It is caused by the notoedres mite, which burrows into the skin and causes intense itching, irritation, and skin thickening. The animal will scratch or bite at the itchy areas. Humans can get scabies from handling an affected animal, characterized by intense itching, worse at night, inside the arms or on the waist, chest, hands, or wrists. The good news is that the mite cannot reproduce on human skin, so the infestation ends within three weeks unless there is additional exposure.
Female mites tunnel underneath the skin of a dog or cat to lay their eggs, which hatch within ten days. The immature mites become adults and lay their own eggs. This cycle takes about twenty-one days. Mites prefer the ears, elbows, hocks, and face. On the cat, they gravitate to the head and neck, and are commonly called "head mange mites." Some dogs will shake their ears frequently, which causes ear swelling. Crusty, intensely itchy ear tips are an important sign. As a test, if you rub the edge of the ear between your fingers, the dog will immediately scratch on that side. Continuous scratching and biting lead to hair loss, crusting, serum seepage, scabs, and small, itchy red bumps, and eventually to pyoderma, a secondary bacterial infection. In its final stages, scabies results in thick, darkly pigmented skin.
The diagnosis of scabies is made by skin scrapings or a skin biopsy of the patches of baldness. It cannot be made simply by observation, because it resembles other skin conditions like ringworm, demodectic mange, and allergies, which require different treatment. However, locating these mites microscopically can be difficult; in these cases, observing for typical signs of sarcoptic mange and treating accordingly is the only alternative.
The treatment consists of weekly injections of Ivermectin for up to four weeks. However, Collies, Shetland Sheepdogs, Old English Sheepdogs, and other herding breeds do not tolerate Ivermectin. For these dogs, multiple dips in the insecticides Lyme Sulfur or Paramite are recommended after clipping the affected areas. Dandruff shampoos can also help. Cortisone relieves the itching. Infected sores can be treated with topical antibiotics.
Because sarcoptic mange is so contagious, all household pets must be treated, whether they are symptomatic or not. In addition, proper nutrition and exercise are important in fighting this condition.
Cheyletiella mange is also known as walking dandruff. It is caused by a large red mite that is often found in kennels, and it is highly contagious. Also called a fur mite, it lives on the skin surface, and can die quickly when removed from its host. It looks like a bad case of dandruff over the top of the neck and the back. Itching is mild. The diagnosis is made by either locating the mite on the animal or through dandruff scrapings examined microscopically. The treatment is an insecticide dip. The kennel should also be treated with an insecticide.
The most common type of mange is demodectic mange or demodicosis. Caused by a microscopic mite that lives in the skin called Demodex canis, it is not contagious. It is found mostly in young dogs, who acquire it from their mothers. The mites are transferred from mother to pup during the first few days of life. An older pup cannot pick up Demodex mites, and puppies raised by hand will not acquire them either. It is not transmitted to humans or spread among adult dogs. The mites produce a substance that can lower a dog's natural resistance to them, and in this way they multiply. Demodectic mange is more common in oily-skinned shorthairs and pubescent dogs. Predisposition to demodicosis seems to be hereditary.
Localized demodectic mange can last for up to a year. The first sign is a small, hairless patch near the eye, chin, or forelegs that doesn't itch much. For young dogs, there is a 90% chance it will clear up by itself by fourteen months of age, unless there is a family history of demodicosis, in which case it drops to 50%. For unknown reasons, in a small number of dogs it will continue to spread. An adult dog may also occasionally develop localized demodicosis. There is hair thinning around the eyelids, lips, corners of the mouth, and the front legs, presenting a moth-eaten appearance. In most dogs, after one to two months the hair begins to grow back, and in three months the skin is healed. Topical insecticide preparations can also be used, but often it is better to allow the condition to resolve on its own.
Generalized demodicosis is characterized by multiple hair loss patches on the head, legs, and trunk that coalesce to form large bald areas. Hair follicles are plugged with mites and debris, and the skin forms sores, crusts, scales, and bald areas, with draining sinus tracts. Lymph nodes may be enlarged. At this point, the dog becomes susceptible to other serious illnesses.
In 30% to 50% of dogs under the age of one year, recovery occurs without treatment. However, treatment is usually recommended to facilitate recovery. An older dog should not develop generalized demodicosis unless it has an underlying problem with its immune system, possibly even cancer.
Generalized demodicosis is diagnosed by skin scrapings. It can be treated with an insecticide ointment to the infected parts three times daily. Relapse is possible, but most dogs that relapse do so within six to twelve months of the end of treatment. Older dogs may never be cured, and treatment will have to be chronic.
Traditional treatment includes dips of Mitaban, a potent insecticide, every week or two, preceded by a hair clipping and benzoyl peroxide shampoo to clear up skin infections and open the hair follicles, where the mites live. Side effects include drowsiness, vomiting, diarrhea, and uncoordination. Mitaban should not be used on small dogs or very young puppies. When skin scrapings are negative twice in a row, the dip and bath regimen is stopped, and the dog is rechecked in one month.
Newer treatments include Interceptor, also used as a heartworm preventative, administered daily. However, this is an expensive alternative because it has to be continued for three months.
Ivermectin is a heartworm preventative that can be given daily to treat generalized demodectic mange. It is cheaper than Interceptor but tastes bad, and may have to be injected.
Another type of demodicosis is demodectic pododermatitis, or demodectic mange of the paws. Old English Sheepdogs and Shar-peis are particularly susceptible to this. Biopsy may be needed to find the mites and make the diagnosis.
Good nutrition, control of other parasites such
as worms and fleas, and keeping up with vaccinations are all important factors in prevention, although alternative veterinarians believe that vaccination actually lowers an animal's resistance to demodicosis. They recommend homeopathy, fasting, and various vitamins and minerals, along with applying fresh lemon juice to the affected area. All veterinarians agree that cortisone should never be used to treat demodectic mange.
The most common feline parasite is the ear mite, which produces a "coffee-grounds" discharge and intense itching, treated with an oil preparation in the ears. Dogs can pick up ear mites from cats, and must also be treated. If you think your cat has mites, consult your veterinarian for diagnosis and safe treatment, because cats are more sensitive to insecticides than dogs.
Although cats are less likely to get the other types of mange than dogs, it is still important to maintain strict hygiene in the cat's living area. Besides the recommended medical treatment, make sure to disinfect bedding and surrounding objects to prevent parasite reinfestation.