Mites and Mange

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Mites & Mange

For centuries, “mange” was a word used to describe almost all skin diseases of dogs. A “mangy dog” was accepted as being a miserable, run-down and scrawny animal.

Today, however, mange is known to be a specific skin disease due to invasion of the skin by tiny parasites called mites. There are two common types of mites which cause mange: demodectic and sarcoptic mange. The two manges are quite different.

Demodectic Mange

Demodex mite
This is caused by the mite Demodex canis, and is the more common form of mange. Most healthy dogs have this mite present in small numbers as a normal inhabitant of their skin and it causes no problems.

Only when these mites multiply and populate the skin in their thousands do they cause trouble. Most dogs do not “catch” demodectic mange – it develops from mites already present.

Demodectic mange can progress from a simple skin condition to a severe problem if there is a failure of the dog’s immune system to prevent spreading. This may occur in a debilitated dog or a dog suffering from another generalised disease such as distemper or infectious hepatitis.

At what age are dogs affected?
The disease occurs typically in young dogs less than 12 months of age, however, exceptions do occur.

Signs and diagnosis:
There are two distinct types of demodectic mange: firstly there is a mild form localised to only a few sites, usually around the head (especially the eyelids, corners of the mouth and under the jaw) and forelegs. Patches of hair loss are seen. There may be a slight itching, but often the dog is not concerned. Usually only one to five patches are present.

The second type is a severe form, where hair loss is widespread over the body, and is called “generalised” demodectic mange. This form is a serious problem and may be incurable in some dogs. When the resistance of the host dog falls, demodex mites may breed to produce tens of thousands of offspring. Frequently the skin becomes secondarily infected with bacteria, and pustules (swollen pus-filled pimples) develop. These may be itchy, causing further damage when the dog scratches itself.

Diagnosis of demodectic mange is made by a vet taking skin scrapings and observing large numbers of mites when the sample is viewed under a microscope.

Mild cases mostly clear up by themselves in about a month. For this reason, many different treatments have been claimed to produce a cure, but preparations containing benzyl benzoate, malathion, lindane and rotenone seem to be most effective. Treatment of generalised mange must be supervised by a vet, since these drugs are toxic. In severe cases, treatment is prolonged and may be unsuccessful. However, many dogs improve with age and the problem may resolve once the dog is sexually mature.

Sarcoptic Mange

Sarcoptes mite
Scabies is a mange caused by a mite called Sarcoptes scabei. This mange is very different to demodectic mange.

Diagnosis and distribution:
Dogs of any age may be infected. The areas most commonly involved are the ears (especially the edges of the ears) and the elbows, although any area of the body may be affected. These areas become red and itchy. Hair usually falls out and the skin becomes flaky and sometimes crusty. The dog develops an intense itch and will rub and scratch vigorously at the affected areas.

Distribution of Sarcoptes

Who can catch scabies?
Scabies is highly contagious to other dogs and may even infect owners if they are in close contact with their dog.

Treatment is always necessary. Scabies will not get better by itself and the intense itching causes dogs to mutilate their skin. Dips such as malathion, ronnel or lime sulphur can be applied weekly until the skin clears up. This may take a month or more. Ointments containing benzyl benzoate, sulphur and other drugs which kill mites are available from vets and some pharmacies. These can be used if only small areas are affected. Spot-on preparations, such as Revolution, can also be used.

Sulfurated Lime
A combination of sulfur and lime (sulfurated lime) is used to kill bacteria, parasites and fungal infections on pets including mange demodex mites, sarcoptes scabiei mites, and ringworm. Sulfurated lime also relieves itching caused by parasites and ringworm.

Solutions of sulfur and lime are used as a rinse or dip every 5-7 days to treat mange (demodex) infections. Treatment is repeated for several weeks until skin scrapings have been clear of mites for at least a month. Sulfurated lime is safe to use on dogs, cats, puppies, and kittens at a dilution of four ounces in one gallon of water. If this concentration does not clear the mite infection, the concentration of sulfurated lime can be doubled to eight ounces per gallon of water.

Unfortunately, sulfur causes an offensive odor and the dip should be applied in a well ventilated room. The smell becomes less noticeable after the dip dries. Dip is left on the skin and is not towel dried, and your pet is not washed or allowed to get wet between treatments. Sulfurated lime dips stain jewelry, porous surfaces such as cement, and the white or light-colored coats of pets. The stained coat returns to a normal color over time. Bathing your pet with a benzoyl peroxide shampoo before dipping opens skin follicles and increases mite exposure to the dip.

Amitraz Dips
Amitraz is a chemical (triazapentadiene) that kills insects and spiders on plants and pets. The following recommendations help make the dip effective and safe for you and your pet:

  • Don’t use on pets with deep, draining bacterial infections. Clean up skin infections first.
  • Clip your pet’s hair unless it is naturally short.
  • Bathe your pet with a benzoyl peroxide shampoo before dipping. This bathing opens skin follicles and increases mite exposure to the dip.
  • Put protective eye ointment in your pet’s eyes and cotton balls in the ears to avoid getting dip in them. Gently sponge areas around your pet’s head and don’t get dip in the lips or mouth.
  • Cover the entire rest of your pet with dip.
  • Leave the dip on and do not towel it off or rinse it off. Don’t let your pet swim or become wet between treatments.
  • Repeat the dip every 1-2 weeks until skin scrapings have no live or dead mites for at least a month. Skin scrapings are taken from bald areas and from normal-haired areas.
  • When applying the dip on your pet, wear protective clothing and remove jewelry, which is discolored by amitraz.
  • Work in a well-ventilated place but do not allow your pet to get cold.

Side effects of Amitraz

Amitraz is a powerful medication and it can cause side effects in dogs. Most dogs become lethargic after being dipped. Amitraz is most likely to be toxic to toy breeds, senior pets, weak pets, cats, and rabbits. Toxic effects include high blood sugar, vomiting, diarrhea, unsteadiness (ataxia), and slow heart rate.

If sulfurated lime or Amitraz don’t clear the infection using ivermectin may help clear mange

Ivermectin is potentially dangerous if they are purebred or mixed breed herding dogs:

  • Australian Shepherd
  • Border Collie
  • Collie
  • German Shepherd

Ear Mites

Inflammation of the ear canal, or otitis externa, can be caused by a number of factors, such as parasites, microorganisms, foreign bodies, tumors, and underlying dermatological (skin) disease. Ear mites are parasites that often can cause otitis externa. However, the incidence is much lower than often thought. In my experience, less than 10 percent of all ear problems in dogs that I have treated are the result of ear mites. Ticks and fleas are other examples of parasites commonly found in canine ear canals.

An important point to remember is that ear mites are parasites. Therefore, for your dog to have ear mites, it must have had direct contact with another pet infested with ear mites. So if your veterinarian diagnoses one animal in your house with ear mites, it is best to have all of your animals examined for possible infestations.

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