Mite Infestation (Mange, Acariasis, Scabies) in Dogs — Dog Owners — Merck Veterinary Manual

Mite Infestation (Mange, Acariasis, Scabies) in Dogs

, DVM, PhD, DACVM, Kansas State University

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. Most types of mange are highly contagious. Both dogs and cats are very susceptible. Horses and other domestic animals can also be infected. There are several types of mange that affect dogs, including canine scabies (sarcoptic mange), ear mites (otodectic mange), walking dandruff (cheyletiellosis), and trombiculosis.

Canine Scabies (Sarcoptic Mange)

This form of mange is caused by the mite Sarcoptes scabiei var canis. This highly contagious parasite is found on dogs worldwide. It is often called canine scabies. Although the mites that cause mange prefer dogs, humans and other animals that come in contact with an infected dog may also become infected. The entire life cycle (17 to 21 days) of these mites is spent on the infested dog. 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 dog is infested, part of the body affected, number of mites transmitted, and the individual dog’s health and hygiene.

Canine scabies is caused by the Sarcoptes scabiei canis mite.

Not all dogs 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 dog 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. Dogs with longterm, recurring mange develop oily dandruff (seborrhea), severe thickening of the skin with wrinkling and crust build-up, and oozing, weeping sores. Dogs affected this severely can become emaciated and may even die.

“Scabies incognito” is a term used to describe hard-to-diagnose mange. If a dog is regularly bathed and has a well-groomed coat, the mites might be hard to find, even if the dog shows signs of infestation such as itching. The other typical signs of mange—crusts and scales on the skin—are removed by regular 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. Mange is very highly contagious and can spread easily between animals of different species and even to humans. Thus, you should ask your veterinarian for advice on how to avoid contracting mange from your pet.

Treatment should include all dogs and other animals that have been in contact with one another. It may be necessary to clip the hair. The crusts and dirt should be removed by soaking with a medicated (antiseborrheic) shampoo, and an anti-mite dip applied. 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. Some internal mange medications are also used for heartworm prevention, so your veterinarian may want to test your dog for heartworms before treatment. Treatment for secondary infections may also be necessary.

Ear Mites (Otodectic Mange)

This form of mange is caused by Otodectes cynotis mites. These mites often infest the external ear, causing inflammation of the ear canal in dogs and especially 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). In dogs with normally upright ears, the external ear may droop. The intensity of the itching varies and may be intense. In severe cases, the external ear may be inflamed and produce pus; a torn eardrum is also possible. Dogs with ear mites should be treated with a parasiticide in the ears or on the whole body. Your veterinarian will recommend an appropriate treatment plan that includes medication and ear cleaning instructions. Animals that have contact with infested dogs should also be treated.

Walking Dandruff (Cheyletiellosis)

Cheyletiella yasguri mites cause walking dandruff in dogs. (The dandruff that is seen “walking” is actually the mites moving about on the skin of the dog.) Although these mites often stay on their preferred hosts, infections across species are possible. Walking dandruff is very contagious, especially in kennels, catteries, or multi-pet households. Regular use of certain insecticides to control flea infestations has a side benefit of often controlling the mites that cause walking dandruff. Humans can also be infested with these species of mites. Mites that cause walking dandruff spend their entire 3-week life cycle on their host but can also live up to 10 days in the environment.

Scaling of the skin and infestation along the back are common signs of walking dandruff. Intense itching is frequent, though some animals do not itch at all. Pets that show no signs can carry the mites and transmit them to other pets and humans.

Cheyletiellosis is diagnosed by looking at an animal’s skin and examining skin and hair samples with a microscope to identify the presence of mites. The mites and eggs may be hard to find, especially on animals that are bathed often.

In many cases, veterinarians will prescribe topical or body-wide treatments with an insecticide to eliminate the mites. In addition, treating the pet’s environment is necessary to kill mites in bedding, carpets, and other areas. Insecticidal treatment of kennels and other multi-pet communities is required to halt mite infestations.

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Owners of pets infested with these mites may want to check with their physicians regarding medication and other steps to control mite infestations in themselves, their family members, and the home environment. It is very easy for these mites to spread from pets to owners.

Canine Demodicosis

The mites that cause canine demodicosis live in small numbers in the hair follicles and sebaceous glands of all dogs. This is normal and causes no signs of disease. However, for reasons not clearly understood, some dogs have large numbers of Demodex canis mites, resulting in inflammation and hair loss. There is evidence of hereditary predisposition for this condition in some dogs. It is strongly suspected that suppression of the immune response to these mites may play a role.

There are 2 clinical forms of canine demodicosis: localized (limited to a small area) and generalized (found on the entire body). Localized demodicosis is usually seen in dogs less than 1 year old. Affected dogs will have 1 to 5 small, isolated areas that are usually hairless, red, and scaly. Itching is mild or absent. A few cases of localized demodicosis progress to the generalized form, though most cases resolve without treatment.

The generalized form of demodicosis can occur in young dogs (juvenile-onset) or in adults (adult-onset). Affected dogs have severe disease with widespread inflammation of the skin. Juvenile-onset generalized demodicosis is the result of an inherited immune system defect. On the other hand, adult-onset generalized demodicosis is often associated with an underlying disease that has suppressed the immune system (such as cancer, Cushing disease, hypothyroidism, or diabetes). Both types of generalized demodicosis can cause hair loss, reddened and swollen skin, increased pigmentation (darkening of the skin), raised lumps that look like acne, and scabs. Secondary bacterial infections (pyodemodicosis) are common. Many dogs with generalized demodicosis also have inflamed foot pads. Other signs can include enlarged lymph nodes, lethargy, fever, and pus-filled inflammation of the deeper layers of skin.

Laboratory analysis of deep skin scrapings is usually used to confirm a diagnosis of demodicosis. In addition, your veterinarian will also want to test your dog for other infections or diseases that may have suppressed the immune system.

Cases of localized demodicosis often resolve without treatment. Generalized demodicosis is a serious disease that requires medical treatment. The outlook for these cases is guarded. Medicated shampoos and dips are often used to treat demodicosis. Prescription medications to kill the mites may be required. In cases where secondary bacterial infections are present, antibiotics may also be prescribed. Skin scrapings are taken at monthly intervals to monitor the number of mites on the dog.

Owners of dogs with demodicosis should understand that treatment of generalized demodicosis can take several months. The prescribed antiparasitic treatment must be continued until at least 2 consecutive negative skin scrapings have been obtained at monthly intervals. Some dogs may need several months of treatment. Recurrence within the first year of treatment is not uncommon.

Because it may be inherited, dogs with demodicosis should not be bred.

Trombiculosis

Trombiculosis is a type of mange caused by the parasitic larval stage of mites of the family Trombiculidae (chiggers). Adults and nymphs look like tiny spiders and live on rotting material. Dogs acquire the larvae by lying on the ground or walking in suitable habitat.

The larvae attach to the host, feed for a few days, and leave when engorged. 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 crusts. Intense itching can persist even after the larvae 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 6-legged mite larvae.

Treatment for dogs and other pets with trombiculosis follows the pattern for the general treatment of mange (see above). Medications to kill these mites on your pet may be different from those prescribed for other types of mites. Follow your veterinarian’s treatment program. 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.

For More Information

Also see professional content regarding mange.

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Parasitic Mites of Humans

ENTFACT-637: Parasitic Mites of Humans | Download PDF

by Michael F. Potter, Extension Entomologist
University of Kentucky College of Agriculture

Mites are very small arthropods which are closely related to ticks. Mite larvae have six legs whereas the nymphal and adult stages have eight. Most species of mites are pests of agricultural crops. However, certain types of mites are parasitic on humans.

Chiggers

Chiggers are the larvae of a family of mites that are sometimes called red bugs. The adults are large, red mites often seen running over pavement and lawns. Chiggers are extremely small (0.5 mm) and are difficult to see without magnification. The six-legged larvae are hairy and yellow-orange or light red. They are usually encountered outdoors in low, damp places where vegetation is rank and grass and weeds are overgrown. Some species also infest drier areas, however, making it difficult to predict where an infestation will occur.

Chiggers overwinter as adults in the soil, becoming active in the spring. Eggs are laid on the soil. After hatching, the larvae crawl about until they locate and attach to a suitable host. The larvae do not burrow into the skin, but inject a salivary fluid which produces a hardened, raised area around them. Body fluids from the host are withdrawn through a feeding tube. Larvae feed for about 4 days and then drop off and molt to nonparasitic nymphs and adults. Chiggers feed on a variety of wild and domestic animals, as well as humans. The life cycle (from egg to egg) is completed in about 50 days.

Most people react to chigger bites by developing reddish welts within 24 hours. Intense itching accompanies the welts, which may persist for a week or longer if not treated. Bites commonly occur around the ankles, waistline, armpits, or other areas where clothing fits tightly against the skin. Besides causing intense itching, chigger bites that are scratched may result in infection and sometimes fever. Chiggers in North America are not known to transmit disease.

Persons walking in chigger-infested areas can be protected by treating clothing (cuffs, socks, waistline, sleeves) or exposed skin with tick repellents. Some repellents should only be used on clothing; and it is important to follow label directions. People who suspect they may have been attacked by chiggers should take a soapy bath immediately and apply antiseptic to any welts. A local anesthetic will provide temporary relief from itching.

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Regular mowing and removal of weeds and brush make areas less suitable for chiggers and their wild hosts. Mowing also enhances penetration and performance of miticides, should they be required. Chigger populations can be further reduced by treating infested areas with residual miticides. Applications should be thorough but restricted to areas frequented and suspected of being infested.

Human Scabies

The sarcoptic itch mites, Sarcoptes scabei, infest the skin of a variety of animals including humans. The types of Sarcoptes inhabiting the skin of mammals are all considered forms of Sarcoptes scabei and can exchange hosts to some degree. (For example, Canine scabies can be temporarily transferred from dogs to humans, causing itching and lesions on the waist, chest and forearms.)

Human scabies mites are very small and are rarely seen. They commonly attack the thin skin between the fingers, the bend of the elbow and knee, the penis, breasts, and the shoulder blades. The mites burrow into the skin, making tunnels up to 3 mm (0.1 inch) long. When they first burrow into the skin, the mites cause little irritation, but after about a month, sensitization begins. A rash appears in the area of the burrows and intense itching is experienced.

Scabies mites are transmitted by close personal contact, usually from sleeping in the same bed. Bedridden individuals in institutions (e.g., nursing homes) may also pass the mites from caregiver to patient. The adult fertilized female mite is usually the infective life stage. She adheres to the skin using suckers on her legs and burrows into the skin where she lays her oval eggs. In 3 to 5 days these eggs hatch into larvae and move freely over the skin. Soon they transform into nymphs and reach maturity 10 to 14 days after hatching.

A scabies infestation should be handled as a medical problem and is readily diagnosed and treated by most physicians. (Confirmation requires isolating the mites in a skin scraping.) The first step to control a scabies infestation usually involves softening the skin with soap and water to make sure the pesticide treatments can penetrate well. An evening bath followed by overnight treatment works best. A total body (neck- down) application of topical pesticide medication should remain for 8-12 hours before showering in the morning. Commonly used products include lindane (Kwell ™), permethrin (Elimite ™) and crotamiton (Eurax ™). Follow directions on the product package carefully.

Because the symptoms of scabies mite infestations are delayed by about a month, other members of the household besides those showing symptoms may be harboring the mites. It is important that everyone in the infected family or living group go through the treatment regime. A second treatment may be necessary to eliminate an infestation of scabies mites, but patients should avoid overzealous pesticide treatment since itching may persist for a week or more after treatment and does not necessarily indicate treatment failure.

Scabies mites cannot live off of a human host for more than 24 hours. Therefore, insecticide treatment of premises is not warranted. It is recommended, however, that coincident with treatment, the clothing and bedding from infested individuals be washed in hot water or dry cleaned.

Bird and Rodent Mites

Parasitic mites that occasionally infest buildings are usually associated with wild or domestic birds or rodents. Bird and rodent mites normally live on the host or in their nests, but migrate to other areas of the structure when the animal dies or abandons the nest. Rodent mites often become a nuisance after an infestation of mice or rats has been eliminated. People usually become aware of the problem when they are attacked by mites searching for an alternate food source. Their bites cause moderate to intense itching and irritation. Rodent and bird mites are very tiny, but usually can be seen with the naked eye. They are about the size of the period at the end of this sentence.

The first step in controlling bird or rodent mites is to eliminate the host animals and remove their nesting sites. Often, the nests will be found in the attic, around the eaves and rafters, or in the gutters or chimney. Gloves should be used when handling dead animals. A respirator should also be worn when removing nest materials to avoid inhaling fungal spores and other potential disease-producing organisms associated with the droppings.

After nests are removed, the areas adjacent to the nest should be sprayed or dusted with a residual insecticide such as those products labeled for flea control. Space or ULV treatments with non-residual materials (e.g., synergized pyrethrins) can be used in conjunction with residual sprays. Space treatments are especially useful when the mite infestation has dispersed widely from the nesting site. In this case, more extensive treatment with residual and non-residual insecticides may also be necessary in other areas of the structure where mites are observed. A vacuum cleaner or cloth moistened with alcohol can be used to eliminate mites crawling on open surfaces.

CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.

Of course, ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE!

entomology.ca.uky.edu

Dog Mites in Humans

Mites are small parasites that live in and around the skin of a host animal, such as a dog, cat or human. Occasionally, these mites can be transmitted between a pet and the owner. Dogs who are suspected to have mites of any type should be taken to a veterinarian immediately for treatment. Owners who think they may have caught mites from their dog should also seek the attention of a health care professional.

Types

Two types of mites that can be spread between dogs and humans are known as sarcoptic mites and demodectic mites. However, veterinarians Holly Nash and Race Foster both note that these mites are usually species-specific. This means that there are specific species for dogs and humans. However, this does not mean that there is no cross contamination that occurs.

Transmission

A human can become infected with canine mange mites in several different ways. The mites can crawl off an infected dog and onto furniture, clothes and other items, where the mites wait for a new host to come into contact with the item. Sarcoptic mites and demodectic mites can also be transferred by simple physical contact with an infested dog. Fortunately, these mites cause only temporary issues and usually die off, as they are not suited for life on humans.

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Symptoms

Canine mange mites that have managed to burrow into the skin of a human will cause only temporary discomfort. The affected person may experience some inflammation or a skin welt, similar in appearance to a mosquito bite. Itching may also occur, though this too is usually only temporary. However, it is possible that individuals with a compromised immune system may suffer from more advanced cases associated with the transference of canine mites.

Diagnosis

Canine mites that manage to get into a person’s skin are generally a limited issue. Most cases will resolve before the patient ever enters the doctor’s office. However, if the issue persists and mites are suspected based on the characteristic lesions on the skin, the doctor may need to take skin scrapings. These skin scrapings will then be examined beneath a microscope to confirm the presence of mites.

Treatment

Once mites have been identified, the home will need to be thoroughly vacuumed. Clothing and bedding should be washed in hot water and dried on a high heat setting to kill off the mites. The affected person will require a medicated cream, such as permethrin, that is applied to the affected area to kill the mites. Some doctors may recommend that all members of a household receive treatment to ensure that the mites do not spread and cause reinfections.

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Demodex in Dogs

Most Common Symptoms

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What is Demodex ?

Generally, once your dog has had an infestation of demodex and the mites have been completely eliminated, they do not become re-infested with the mites. This is because your dog’s immune system is now able to recognize and eliminate any new demodex mites. Some dogs that have a weak immune system will not be able to eliminate the mites without medical intervention.

Demodex, also known as demodectic mange, in dogs is a mite infestation on your dog’s skin. The mites are tiny, eight legged, cigar shaped, and feed in the hair follicles and oil glands of the skin. Most cases of demodex are self-limiting, meaning your dog is able to stop the growth and reproduction of the demodex mites and will also repair the damage that was done by the mites.

Symptoms of Demodex in Dogs

When demodex first appears, it may just look like a small spot of hair loss, possibly from rubbing the area. However, if you notice any crusting on the skin or the hair loss spreads contact your veterinarian for an appointment. Symptoms of demodex to look for include:

  • Hair loss in patches
  • Rubbing their face or head
  • Redness or inflammation of the skin
  • Excessive oil on the skin
  • Crusting on the skin
  • Paws that are swelling

Types

Demodex has three distinct varieties.

Localized

This type of demodex will affect only a few parts of the body, usually the face. It will appear as just a small lesion around the face and is commonly seen in puppies. Most cases of localized demodex will resolve without any treatments as the puppies immune systems mature.

Generalized

This type of demodex will affect larger areas of skin or possibly the entire body. Generalized demodex will many times cause secondary bacterial infections. These bacterial infections will cause intense itching and a foul odor. It can be very difficult to fully eliminate all the mites.

Demodectic Pododermatitis

This type of demodex is located on the feet only. It causes secondary bacterial infections that are located between the pads and the toes. This type is the most difficult to fully cure.

Causes of Demodex in Dogs

Demodex is caused by the Demodex canis, which is a parasite or mite that lives in the hair follicles of dogs. All dogs have these mites living on their skin but will not have a reaction to these mites unless their immune system is deficient.

Demodex is most common in puppies and dogs that have immature immune systems. The mites will multiply uncontrollably when your dog’s immune system is immature or weak and unable to properly dispose of the excessive mites. Most adult dogs will be able to fight off the excessive mites without needing medical intervention. Older dogs may also show symptoms of demodex as their immune systems begin to decline and with age.

Diagnosis of Demodex in Dogs

Your veterinarian will begin by taking a complete medical history on your dog. They will also ask you about any changes in diet or environment. Then, your veterinarian will complete a full physical examination on your dog, paying close attention to any bald spots or noticeable lesions.

Your veterinarian will do a complete blood count and will also do a skin scraping of an affected area. The skin scraping will be placed under a microscope and your veterinarian will look for mites. Demodex canis mites are fairly easy to spot under the microscope.

If your dog is a mature dog, your veterinarian may also search for the reason the Demodex canis mites were able to multiply uncontrollably. There is usually an underlying cause that is suppressing the immune system and sometimes it is extremely difficult to find what that cause is.

Treatment of Demodex in Dogs

Once your veterinarian has diagnosed demodex they will begin treatments to get rid of the overgrowth of mites. Anti-mite creams can be used as well as anti-inflammatory creams and corticosteroid creams. Your veterinarian may also recommend using benzoyl peroxide on larger areas. Your veterinarian will probably trim the hair around the affected areas. This will allow the prescribed creams to work more effectively on the affected areas.

Some cases of demodex may require the use of anti-parasitic medications. Your veterinarian will prescribe the medications they feel will work best on your dog. Antibiotics may also be used in cases where bacterial infections from the demodex have occurred.

Recovery of Demodex in Dogs

Most cases of demodex are treatable. Dogs that are suffering from a weak or suppressed immune system will be much more susceptible to other diseases and conditions as well as relapses of demodex. Dogs that have immature immune systems, such as puppies, will generally recover from demodex and will not have a relapse.

Speak with your veterinarian regarding your dog’s prognosis. Dogs that have weak or suppressed immune systems should not be used for breeding. Puppies who have developed a case of demodex can still be bred when they are older as long as the demodex does not recur.

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