Demodex in cats and dogs is an infestation of the Demodex mite that causes skin diseases. It is often serious because of the underlying disease that prompts an immune deficiency that allows the mites to thrive. In cats, D. cati is the cause of Demodicosis in cats. It is a serious disease because the cat may have feline leukemia virus, cancer, immunodeficiency virus, or other conditions that have weakened its defenses, resulting in the proliferation of the mites. Loss of fur around the eyes and on the face is usually the symptom of the mites. Other symptoms may be itching, redness, and hair loss. Prescription ointment can control the mites, but the underlying cause must also be investigated and treated.
Veterinarians will sometimes do skin diagnostic tests for Demodex in cats, and they do not always appear in the skin scraping. This is because D. cati lives in the hair follicles, and may not be seen under the microscope. Cats do not get Demodex as often as dogs, and when they have it, there are usually only a few of the mites living on their body. Treatment is often by prescription ointment, and some success has been had with a lime sulfur bath once a week for about six weeks.
There is another type of Demodex found in cats that live on the Gulf Coast of the U.S. This mite is called D. gatoi. It is a mite that lives in the layers of the skin rather than in the hair follicles. The mites cause severe itching and they are treated with pesticides that kill the mites on the cat’s skin.
The cause of Demodicosis or red mange in dogs is D. canis. Almost every puppy has some D. canis mites by the time it is a few weeks old since they are transferred from the mother dog to her puppies. D. canis is not contagious from one dog to another after the pups are a few weeks old and their immune system is able to fight off an excess of the mites. The immune system of a dog is not completely mature until it is 12 to 18 months old, but they are usually able to fight off the mites. It is extremely rare for a human to get D. canis from a dog, but it does occasionally happen. Dogs with red mange resulting from this mite should not be bred because of the increased chance that their pups and future generations will also have Demodicosis.
The symptoms of red mange in dogs are itching, hair loss, redness, and lethargy. As the mite infestation increases, the dog’s skin becomes redder and dark brown from pigmentation changes. The dog is very miserable when the disease gets to advanced stages because of secondary infections and pain from open lesions. Treatment is a chemical pesticide that is prescribed by the veterinarian, but dogs with weakened immune systems and illness do not usually tolerate the treatment very well. Serious side effects can result from the use of chemicals to treat red mange. They should not be used in herding breeds, such as collies or sheep dogs and others who may have the MDR-1 gene mutation. This gene mutation means that the dogs with it are more susceptible to the toxic antiparasitic drugs.
Natural treatment, or homeopathic treatment for cats and dogs, is also used by some people to rid the animals of the mites. Veterinarians who do not use harsh pesticides to rid cats and dogs of mites say that the chemicals in the pesticides affect the natural function of the hypothalamus and other body parts of the animal. There are natural minerals, vitamins, and supplements that these practitioners use to treat mites. Some animal doctors believe that changing the dog’s diet from kibble to raw food is all that is needed to strengthen the dog’s immune system so that the animals can fight off the mites naturally.