Mite Infestation (Mange, Acariasis, Scabies) of Cats
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, 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.
Canine scabies (also called sarcoptic mange) is caused by the mite Sarcoptes scabiei var canis. Although the canine scabies most often occurs in dogs, it can also occur in cats that come in contact with infected dogs. The mites are highly contagious and can also infest people and other animals. The entire life cycle (17 to 21 days) of these mites is spent on the infested animal. Females burrow tunnels in the skin to lay eggs. Mange is easily spread between animals by contact. Indirect transmission, such as through infested bedding, is less common, but it can occur. The incubation period varies from 10 days to 8 weeks, depending on how severely the animal is infested, part of the body affected, number of mites transmitted, and the individual pet's health and hygiene.
Not all animals have signs when they are infested with sarcoptic mange mites. Usually, though, the animal will have intense itching that comes on suddenly. The itching is probably caused by sensitivity to the mites’ droppings. Initially, infested skin will erupt with small, solid bumps. Because the animal scratches or bites itself to relieve the itch, these bumps and the surrounding skin are often damaged, causing thick, crusted sores. Secondary yeast or bacterial infections can develop in the damaged skin. Usually, the sores appear first on the abdomen, chest, ears, elbows, and legs. If the mange is not diagnosed and treated, the sores can spread over the entire body. Animals with longterm, recurring mange develop oily dandruff (seborrhea), severe thickening of the skin with wrinkling and crust build-up, and oozing, weeping sores. Animals affected this severely can become emaciated and may even die.
Scabies incognito is a term used to describe hard-to-diagnose mange. If an animal has a well-groomed coat or is bathed regularly, the mites might be hard to find, even if the animal shows signs of infestation, such as itching. The other typical signs of mange—crusts and scales on the skin—are removed by regular grooming or bathing.
If mange is suspected, your veterinarian will do a physical examination, including collecting skin scrapings and possibly a stool sample. Some clinics might also use a blood test to diagnose mange. If mites are not found, but the signs are highly suggestive of mange, trial treatment is warranted. Because mange can spread easily to humans, you should ask your veterinarian for advice on how to avoid contracting mange from your pet.
Treatment should include all other animals that have been in contact with the infested pet. It may be necessary to clip the hair. The crusts and dirt should be removed by soaking with a medicated (antiseborrheic) shampoo and applying an anti-mite dip. Lime-sulfur is highly effective and safe for use in young animals. Several dips may be required. Alternatively, internal or topical medicines are also effective. Treatment for secondary infections may also be necessary.
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 above). 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 may involve spot-on or injectable therapies, lime-sulfur dips given 7 days apart or a combination of these therapies.
Ear mites (otodectic mange) are caused by Otodectes cynotis mites. These mites often infest the external ear, causing inflammation of the ear canal. 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 but may be severe. 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 or for the whole body. Your veterinarian will recommend an appropriate treatment plan that includes medication and ear cleaning instructions. Animals that have contact with infested cats should also be treated.
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 multi-pet households. 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. However, female mites can live as long as 10 days off of the animal. In areas that have lots of fleas, this type of mange is rare because regular use of certain insecticides to control flea infestations has a side benefit of often controlling the mites.
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 called miliary dermatitis. Some cats may show no signs of infestation but carry the mites and transmit them to other pets and humans.
To diagnose walking dandruff, veterinarians use laboratory tests (such as skin scrapes, flea combing, or tape tests) to identify the presence of mites or eggs. Unfortunately, the mites and eggs can be difficult to find. If no mites are identified but an infestation is still suspected, your veterinarian may prescribe treatment to see if improvement is seen. For treatment, your veterinarian may prescribe weekly dipping in an insecticide to eliminate the mites. Other treatment options include spot-ons, sprays, injections, and oral drugs. Do not use an insecticide on your cat without your veterinarian's approval. Some insecticides are poisonous to cats.
Treatment may last 6 to 8 weeks to eliminate all mites. This may be difficult in catteries or in multi-cat households. Any animals in contact with an infested pet will also need to be treated. 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. Two species of Demodex mites can cause demodicosis. Demodex cati mites are thought to be a normal resident of feline skin. 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, feline leukemia virus infection, feline immunodeficiency virus infection, or cancer.
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 superficial and 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 demodicosis should be tested for ringworm, because the two conditions can occur simultaneously and have similar signs. Cats with generalized demodicosis should be evaluated by a veterinarian to see if another medical condition (such as diabetes) is present. 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 once 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 ("chiggers"). Adults ("harvest mites") 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. In temperate areas, cats and other animals acquire the larvae during the summer and fall. In warmer areas, infestation occurs throughout the year.
The tiny larvae attach to the host, feed for a few days, and leave when engorged. At this point, they are easily identified as tiny, orange-red, 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, if present, 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. 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.
Fur mites (Lynxacarus radovskyi) infest cats quite commonly, but only in certain areas (Australia, Brazil, Hawaii, Florida, North Carolina, and Texas). These mites cause in inflammation of the skin, and signs include a salt-and-pepper appearance of the hair coat, hair loss, and itching. The amount of itching seen varies between cats. Veterinarians diagnose the mite with laboratory tests (such as skin scrapes or tape tests) or by identifying it on the cat's fur. Treatment may include sprays, weekly lime sulfur dips, or injections. It is possible, but unlikely, for people to catch fur mites from their cats.
Also see professional content regarding mange.