Demodectic mange, also known as demodex, demodicosis, puppy mange, follicular mange or red mange, is a disease common to puppies. Demodex symptoms, including the red skin and hair loss, are caused by Demodex mites, which prefers to live in dogs' hair follicles. A mother dog can transfer the mites to her puppies, but otherwise they are not contagious. The immune deficiency that gives rise to the symptoms is inherited.
The Demodex Mite
Demodectic mange is caused by three species of mites: Demodex gatoi, Demodex injai and Demodex canis. These mites are present on all dogs raised by their mothers, as they are passed from mother to pup. Under normal conditions, the mites live on dogs' skin and in their hair follicles without any negative effect. But when a dog's immune system is compromised, the mite begin spreading uncontrollably, causing the hair loss and irritation that characterizes demodectic mange. Because puppies’ immune systems are not fully developed, they are also susceptible to demodectic mange.
Localized vs. Generalized
Demodectic mange is either localized or generalized. Demodex is localized if the dog has four or fewer affected areas and if those areas are confined to his head and feet. Localized demodectic mange typically affects puppies 3 to 6 months of age. It is likely to go away without treatment unless the parents also had the mange as puppies. Generalized demodectic mange creates lesions over the dog’s entire body. Unlike localized demodectic mange, it can appear both in young puppies and in adults. As with the localized type, generalized demodectic mange affecting puppies usually resolves on its own. Generalized demodectic mange is a more severe form of the disease than the localized type; it can cause secondary infections.
Heredity vs. Contact
Demodectic mange is not hereditary. All dogs have the demodectic mite on their bodies in varying degrees. The mites pass from the mother to the puppy through ordinary physical contact. Demodectic mites might also be passed between healthy adult dogs, but disease does not typically occur from these cross contaminations.
Although the mites that cause demodectic mange are spread by contact, the depressed immune system that causes demodex can be hereditary. Puppies naturally have poorly developed immune systems. By contrast, adult dogs should have sufficiently developed immune systems to prevent a demodectic mange outbreak. Dogs that have had adult onset generalized demodectic mange should not be bred.
Diagnosis and Treatment of Demodectic Mange
Demodectic mange is diagnosed with either a skin scraping or a biopsy, which involves removing a larger piece of skin. Microscopic inspection will confirm the mite/lesion pairing that must be present for a diagnosis of demodex. Localized demodectic does not require treatment. However, some veterinarians suggest topical ointments or creams to reduce the symptoms. Generalized demodectic mange is treated using ivermectin or Milbemycin oxime -- Interceptor -- given orally, or by using a dip containing amitraz. Spaying can prevent generalized outbreaks from recurring in adult female dogs. Good nutrition and routine health care can also ensure that a dog is not physically stressed, which will also prevent recurrences or outbreaks of demodectic mange.