Mite Infestation (Mange, Acariasis, Scabies) of Cats
Also see professional content regarding mange.
Mange is caused by microscopic mites that invade the skin of otherwise healthy animals. The mites cause irritation of the skin, resulting in itching, hair loss, and inflammation. All forms of mange are highly contagious. Cats are very susceptible to several types of mange, including canine scabies (see Mite Infestation (Mange, Acariasis, Scabies) in Dogs : Canine Scabies (Sarcoptic Mange)), feline scabies (notoedric mange), ear mites (otodectic mange), walking dandruff (cheyletiellosis), and trombiculosis. Demodicosis is not considered mange, but it is also caused by mites.
Infestation with Notoedres cati mites is a rare and a highly contagious skin disease of otherwise healthy cats. The mite’s appearance and life cycle are very similar to that of the sarcoptic mange mite (see Mite Infestation (Mange, Acariasis, Scabies) in Dogs : Canine Scabies (Sarcoptic Mange)). Mange is readily transmitted between cats by contact. Notoedric mange causes severe itching. Skin crusts and hair loss first appear on the ears, head, and neck, but can spread over the entire body. Veterinarians diagnose notoedric mange by using a microscope to inspect skin scrapings for mites. Treatment involves lime-sulfur dips given 10 days apart. Your veterinarian might also try treatment with other medications.
This form of mange is caused by Otodectes cynotis mites. These mites often infest the external ear, causing inflammation of the ear canal (see Disorders of the Outer Ear in Cats : Mange). Although ear mange occurs in dogs, it is especially common in cats. Ear mites are usually found deep in the external ear canal, but they are sometimes seen on the body. The infested animal will shake its head and scratch its ear(s). The external ear may droop. The intensity of the itching varies. In severe cases, the external ear may be inflamed and produce pus; a torn eardrum is also possible. Cats with ear mites should be treated with a suitable medication in the ears, as well as with whole body drugs, for 2 to 4 weeks.
Cheyletiella blakei mites are the most common cause of walking dandruff in cats. (The dandruff that is seen “walking” is actually the mites moving about on the skin of the cat.) Cheyletiella mites are very contagious, especially in catteries or multipet households. Regular use of certain insecticides to control flea infestations has a side benefit of often controlling the mites that cause walking dandruff. Humans are frequently infested with this mite. Mites that cause walking dandruff have 4 pairs of legs and large hook-like mouthparts. They live on the skin’s surface, and they spend their entire 3-week life cycle on their host.
Scaling of the skin and infestation along the back are common signs of walking dandruff. Intense itching is frequent among infested cats, though there may be no itching at all. Cats may develop skin crusts and many small bumps along their back (See also Fleas of Cats : Flea Allergy Dermatitis). Some cats may show no signs of infestation but carry the mites and transmit them to other pets and humans.
For treatment, your veterinarian may prescribe weekly dipping in an insecticide to eliminate the mites. In addition, treating the household is necessary to kill mites that can survive in bedding, carpets, and other areas.
Demodicosis is caused by Demodex mites. Demodex mites are thought to be a normal resident of feline skin. Two species of Demodex mites can cause demodicosis. Demodex gatoi is smaller and rounder than Demodex cati. It is commonly found in younger cats and is contagious.
These mites do not usually bother their host, but they can cause demodicosis in cats sickened by another disease. Demodicosis can be limited to one or several areas on the head and neck, where it causes hair loss, or it can spread over the entire body. When demodicosis is severe enough to affect the entire body, it causes crusting and fluid-filled sores in addition to hair loss. Whole-body demodicosis can be associated with other system-wide diseases, such as diabetes mellitus.
In some cases of demodicosis, the only sign is overproduction of earwax (see Otitis Externa in Cats). The severity of itching can vary; D. gatoi is more likely to cause severe itching than D. cati. Your veterinarian will diagnose demodicosis by collecting and examining deep skin scrapings for mites. However, the mites can be very difficult to find, and a response to treatment may be the only way to diagnose the infestation. Cats with generalized disease, such as diabetes, should be evaluated by a veterinarian if demodicosis is suspected. The outlook for recovery from whole-body demodicosis depends on the cat’s overall health. Some cases resolve without treatment. Treatment with lime sulfur dips 1 to 2 times weekly for 4 to 5 weeks is usually safe and effective. Infested cats often have a fast response to treatment.
Trombiculosis is a type of mange caused by the parasitic larval stage of mites of the family Trombiculidae. Adults and nymphs look like very tiny spiders and live on rotting material. Cats acquire the larval life-stage as parasites when lying on the ground or walking in a suitable habitat.
The larvae attach to the host, feed for a few days, and leave when engorged. They are easily identified as tiny, orangered, oval dots that do not move. These are usually found clustering on the head, ears, feet, or belly. Signs include redness, bumps, hair loss, and skin crusts. Intense itching can persist even after the parasites have left the animal.
Diagnosis is based on history and signs. Your veterinarian will want to exclude other skin disorders that cause itching, such as allergies (see Allergies of Cats : Airborne Allergies (Atopy)). Diagnosis is confirmed by careful examination of the affected areas. Skin scrapings might also be examined under the microscope for evidence of mite larvae.
Treatment for cats with trombiculosis follows the pattern for the general treatment of mange. Medications to kill these mites may be different than those prescribed for other types of mites. Follow your veterinarian’s treatment program carefully. If the itching has been either severe or extended, antibiotics or other medications may be prescribed to control secondary infections in scratch and bite wounds.
Preventing reinfestation is often difficult. The most useful approach, if feasible, consists of keeping pets away from areas known to harbor mites. You should also avoid bringing your cat into contact with other animals known to have the mites.