When I picked up Pooh Bear* for his walk on Tuesday, I immediately noticed something was off. His left eyebrow, usually bushy, was sparse, as if he had done a face plant and scraped the fur off in the process. Pooh’s parents had noticed the change too and headed to the vet for a diagnosis. The unusual location of the spot, over his eye, made the possibility of a hot spot unlikely. Hot spots can form in response to any kind of irritant but grow and linger when the dog scratches and licks the area. Without a monster tongue or ultra flexible paws, Pooh would have trouble getting enough leverage to create a full on hot spot on his eyebrow. Pooh’s dad’s money was on Demodex and the vet confirmed his suspicion. Little Pooh was suffering from an infestation of mites!
Demodex, a form of mange, is a genus of tiny, parasitic mites that feed on the skin cells and oils found in hair follicles. There are a number of different species which can infect mammals of all kinds (including humans) but demodex canis is the type most commonly found on domestic dogs. Many veterinarians believe that all dogs have a certain number of demodex mites living on their skin and most will never develop a full-blown infestation. But some dogs have fewer of the natural antibodies that help to defend them against demodex and may develop skin lesions in response to nutritional or environmental stress or an otherwise compromised immune system. Demodex is also common in newborn pups with undeveloped immune systems that may be infested by mites living on the mother’s skin when suckling. Despite popular belief, it is demodex does not seem to be hereditary, passed from mother to fetus.
Demodex infestations can be localized, like the single spot above Pooh Bear’s eye, or more generalized and found in multiple spots on the body. Localized infections are easier to resolve and may even do so without any veterinary intervention (however, adult on-set demodex may signify a more sreious underlying cause such as hypothyroidism, adrenal gland disease, or even cancer so it is important to take your pup to the vet to have him checked out). More wide-spread infestations may require closely clipping your dog’s fur, regular dips in benzoyl peroxide and Amitraz (a miticidal treatment), and possibly antibiotic therapy.
It is uncommon (though not impossible) that canine demodex will infect humans and, because demodex mites are likely present on all dogs, there is little risk that a healthy dog that comes in to contact with one suffering from a demodex infection will develop an infection of his own. To eliminate any real risk to others, though, keep your dog away from young puppies and older or sick dogs while he is suffering from a demodex infestation.