Demodectic Mange In Dogs
Demodectic mange in dogs is extremely common. In fact, the mites which cause this mange, Demodex canis or Demodex injai, are present on nearly every adult dog and most people. They don’t usually cause any irritation, however. It is only when the immune system is poorly developed or suppressed, as in very young or elderly dogs, that this skin disease is most likely to become a problem.
Causes
Demodectic mange in dogs is caused by a tiny mite that is about 0.25 mm in size. These mites, either Demodex canis or Demodex injai, normally live on the bodies of virtually all dogs without causing any problems. They live inside hair follicles. Most dogs with a healthy immune system are able to keep the mites under control. The mites only become a problem when a dog has an inadequate immune system. This can occur in very young dogs and puppies who do not yet have a fully developed immune system. It can also occur in older dogs who may have a suppressed immune system for some reason.
The mites live out their entire lives on the dog. They do not need an intermediate host. The mite lays eggs and the eggs hatch. They then mature and grow into adults. It is believed to take between 20 and 35 days for the entire mite life cycle to complete itself.
Most puppies get mites from their mothers during the first week of life through direct contact. When the puppies are nursing the mites transfer themselves to the puppies, usually to the head. Most puppies are immune to the effects of the mites and won’t display any symptoms. However, some puppies will display some signs and you may see symptoms of mange.
Demodectic mange is not caused by a dirty kennel or dirty dogs. If your puppies or dogs display symptoms of mange, the kennel and bedding is not affected. The mites are only found on the puppies and dogs, not the environment. The appearance of demodectic mange depends on a puppy or dog’s immune system.
Symptoms
If your puppy or dog does have an immune system that reacts to the mites then he may develop a few isolated lesions. This is a localized form of mange. Other dogs may have generalized mange if the dog has more than five lesions. This form of mange usually involve the dog’s entire body. In most cases demodectic mange occurs when the puppy or dog is older than four months old.
Signs of demodectic mange include:
- loss of hair
- red, crusty skin
- skin with a greasy, moist appearance
The dog’s hair is most affected since mites like to live in the dog’s hair follicles. The hair loss usually starts around the dog’s muzzle, eyes and elsewhere around the head where the hair is thinner. In some cases the lesions itch, but not always.
With localized mange, when there are five or fewer lesions, your dog will have just a few circular crusty areas. These usually occur on the head and front legs of dogs that are three to six months old. In most cases these lesions will heal themselves as the puppies get older and develop immunity to the mites. However, if there are persistent lesions which don’t heal, they will need to be treated.
In cases of generalized mange where the entire body is affected, there may be hair loss all over the body. The head, neck, stomach, legs, and paws may all be affected. The skin may be crusty and reddened. In some cases it may crack open and a clear fluid may ooze out. The dog may have little hair but the skin may feel oily. In many cases the dog may have a secondary bacterial infection. Some dogs can become very ill with a fever, loss of appetite, and lethargy. Dogs in this condition need veterinary treatment right away.
Diagnosis
If your dog has lesions, or if you suspect that your dog has Demodectic mange, you should take your dog to the veterinarian. Your vet will need to take skin scraping and perhaps perform a biopsy. This will allow him or her to see the mites under a microscope. Under magnification the mites look like tiny alligators. However, the presence of mites alone will not confirm that your dog has Demodectic mange since mites are present on virtually all dogs. Your dog must also have lesions for your vet to diagnose Demodectic mange.
If you have an older dog with Demodectic mange then your vet will need to test your dog for other possible diseases such as Cushing’s, cancer, hypothyroidism, and heartworm disease. These illnesses can sometimes produce some of the same symptoms as Demodectic mange in older dogs.
Treatment
Demodectic mange is usually treated with dips, lotions, and shampoos. Most (some 90 percent) of Demodectic mange cases are of the localized variety which can be treated topically. Goodwinol ointment which contains 1 percent rotenone ointment is often used to treat localized Demodectic mange. A five percent benzoyl peroxide gel applied daily can also be used. Bathing with benzoyl peroxide shampoo, feeding a quality diet, and providing your dog with fatty acids in his diet can also help. In most cases localized lesions will heal on their own if they are cared for properly.
Generalized Demodectic mange requires more aggressive treatment. It is estimated that some 30 to 50 percent of dogs with generalized Demodectic mange will heal on their own but treatment is still advised. However, treatment can take a long time and it can be expensive. Amitraz dips are usually recommended, applied every two weeks. This product is usually sold under the name Mitaban by prescription. When applied to dogs with medium and long hair it may be necessary to clip the dogs short so the dip can reach the skin well. It is suggested to bathe the dogs with a benzoyl peroxide shampoo first. It usually takes between four and 14 dips, at two-week intervals, to treat a dog with generalized mange. Skin scrapings should be taken periodically to check for mites. Continue the dips until the mites are completely eliminated. Dogs are not considered to be fully cured until a year after their final treatment.
Some dogs are sensitive to Amitraz, especially toy or small dogs. They may become nauseated or sleepy. Use the product half-strength on these dogs.
Some veterinarians use Ivermectin products off-label to treat Demodectic mange in dogs. Milbemycin oxime and Moxidectin have also been shown to work off-label against mites. You can talk to your vet about these promising treatments.
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