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Mange – Demodectic in Dogs

Mange is a parasitic skin disease caused by microscopic mites. Two different mange mites cause skin disease in dogs. One lives just under the surface of the skin, while the other resides deep in the hair follicles. Although both mites share similar characteristics, there are also important differences. It is important not to confuse the two types of mange because they have different causes, treatments, and prognoses.
What causes demodectic mange?
Demodectic mange, sometimes just called “demodex” or “red mange”, is the most common form of mange in dogs. It is caused by the Demodex canis, a parasite that lives in the hair follicles of dogs. Under the microscope, this mite is shaped like a cigar with eight legs.
“As long as the body’s immune system is functioning properly, these mites cause no harm. “
All normal dogs (and many humans) have a few of these mites on their skin. As long as the body’s immune system is functioning properly, these mites cause no harm.
Demodectic mange most often occurs when a dog has an immature immune system, allowing the number of skin mites to increase rapidly. As a result, this disease occurs primarily in dogs less than twelve to eighteen months of age. As the dog matures, its immune system also matures. Adult dogs that have the disease usually have defective immune systems. Demodectic mange may occur in older dogs because function of the immune system often declines with age. Dogs who have immune suppression due to illness or certain medications are also candidates for demodectic mange.
Is demodectic mange contagious?
“Demodectic mange is not contagious to other animals or humans.”
No, demodectic mange is not contagious to other animals or humans. Demodex mites are transmitted to puppies from their mother during the first few days of life. Since the mite is found on virtually all dogs, exposure of a normal dog to one with demodectic mange is not dangerous.
Why doesn’t the immune system mature correctly in some dogs?
Development of the immune system is under genetic or hereditary control. Thus, an affected dog often has littermates that are also affected. Owners of littermates should be alerted to watch for the development of mange in their puppies. Because the disease is due to a genetic defect, affected dogs should not be bred, and the parents of the affected dog should not be bred again.
What does demodectic mange do to the dog?
Surprisingly, a dog with demodectic mange usually does not itch severely, even though it loses hair in patches. The hair loss usually begins on the face, especially around the eyes. When there are only a few patches of hair loss, the condition is called localized demodectic mange. If the disease spreads to many areas of the skin, it becomes generalized demodectic mange.
How is demodectic mange diagnosed?
“Your veterinarian will take deep skin scrapings and examine them under the microscope to diagnose this disease.”
Your veterinarian will take deep skin scrapings and examine them under the microscope to diagnose this disease. The finding of larger than normal numbers of Demodex mites in skin scrapings confirms the diagnosis. Occasionally, the disease will be diagnosed by means of a skin biopsy in dogs that have chronic skin infections that have not responded appropriately to treatment.
How is demodectic mange treated?
The treatment may involve oral medication, special shampoos or dips, or topical prodicts. In some cases, especially dogs with generalized demodectic mange, secondary skin infections complicate the condition, requiring antibiotic therapy. Dogs with skin infections often have very red, inflamed skin. This is the source of the term “red mange.”
Is there risk to using Ivermectin?
Ivermectins are a class of drugs that are approved for prevention of heartworm disease in dogs and cats. Ivermectin is a very strong drug that can cause severe side-effects, including death, if it is not administered properly. It is off-label in dogs. Veterinarians do not generally recommend ivermectin usage in collies, Shetland sheepdogs, Australian shepherds, old English sheepdogs, or any other herding breed.
Advantage Multi ®, containing imidacloprid and moxidectin, is now labeled and approved for the treatment and control of generalized demodectic mange, and may be considered for treatment of generalized disease as well.
What is the prognosis for my dog?
Treatment of demodectic mange is generally successful. However, if the immune system is defective, neither the mites nor the infection may respond to treatment. With generalized demodicosis, successful treatment may take a long time.
Following successful treatment, is it likely to recur?
“It is important to treat as soon as a relapse occurs to minimize the possibility of developing uncontrollable problems.”
Because the immune system does not mature until twelve to eighteen months of age, a dog with demodectic mange may have relapses until that age. It is important to treat as soon as a relapse occurs to minimize the possibility of developing uncontrollable problems.
This client information sheet is based on material written by: Ernest Ward, DVM © Copyright 2009 Lifelearn Inc. Used and/or modified with permission under license.

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