Demodex (Dog Mites) Signs, Symptoms and Treatment Options

Almost all dogs have demodex mites. It is normal to have demodex mites in small numbers. In dogs with a mature, healthy immune system the mites are kept in check.   However, in the very old, very young, sick, or pregnant dogs the immune system may be compromised and the mites may increase dramatically in number. When the mites are in very small numbers they cause no clinical signs and are not visible to the naked eye. When there is an overgrowth of mites this can lead to hair loss, red, flaky skin and sometimes secondary bacterial infection.

Demodex mites are not contagious to other dogs under normal circumstances. Dogs can get the mites from their mother during nursing. Fortunately, it is not contagious to human beings, either.

If your dog is diagnosed with demodex it is not necessary to do any special cleaning or disinfection of your home or to avoid contact with your pet.

Juvenile Demodex

This occurs in puppies and young adult dogs. Most of these dogs will have multiple areas of hair loss. Many of these dogs have no symptoms though some can be mildly itchy.

Since about 90% of young dogs with demodex will resolve the problem on their own we do not recommend immediate treatment in these cases. If your pet is not uncomfortable and otherwise in good health we recommend a 4-week monitoring period to determine if it will resolve on its own or will require treatment. At any point, if you feel your pet is uncomfortable or developing sores please contact us. A lot of dogs will look a little worse before they get better. This is completely normal.

There is a lot of information to suggest that dogs who develop an overgrowth of demodex mites have a genetic predisposition to do so. However, there are other factors which determine whether or not your pet will have a problem. Normal stresses of puppyhood which are unavoidable can be enough to cause this condition in some dogs. Fortunately, most dogs who develop this disorder are otherwise healthy and go on to lead completely normal lives.

Since we do believe this condition to be genetically linked we do recommend spaying or neutering. There are also lots of other health benefits to this as well!  Many females will get dramatically worse during heat cycles. Spaying your pet will eliminate this concern.

The good news is demodex is typically very responsive to treatment. About 90% of dogs will be cured with treatment. The remaining 10% usually can be managed with long term medications. Even in the most treatable cases therapy usually lasts at least 6 months.

Adult Onset Demodex

This form occurs in adult dogs (usually over 5 yrs of age).  Most of these dogs did not have an overgrowth of mites as puppies. This form tends to be more severe, though not always. It can also be more difficult to treat.

When a dog who has gone through life with no problems regulating demodex suddenly has a problem we always want to know why. This can happen for a number of reasons. The most common reported causes are underactive thyroid, Cushing’s disease, cancer or immunosuppressive medications. These account for about 50% of adult onset cases. In many cases an underlying cause cannot be found. The likelihood of finding an underlying cause will depend somewhat on how many tests we decide to run. In some cases the demodex may be the first sign of a more serious disease which may not become obvious for several months. If there is an underlying cause which is not treated the demodex likely will not resolve even with the best anti-demodex medications.

Like young dogs who develop an overgrowth of demodex mites many veterinarians believe that these older dogs have something in their genetic makeup which makes them vulnerable to a mite proliferation.

Adult onset demodex carries a fair to good prognosis. It can be more difficult to treat than in young dogs but is worth the effort.