Scabies is the name for a skin disease caused by a member of the Sarcoptes genera of mite parasites. Another name for scabies is "sarcoptic mange". Scabies is normally an intensely uncomfortable skin disease due to itchiness (pruritus) caused by the parasite. This pruritus is thought to be due to a hypersensitivity to proteins found in the fecal matter produced by Sarcoptes mites as they burrow through the layers of the epidermis. The classic case of canine scabies is an intensely pruritic dog who scratches and rubs almost constantly and who cannot seem to be comfortable.

What is the pinnal-pedal reflex?

Classically, when the ear flaps (pinnae) of a dog with scabies is gently rubbed, the dog's hind leg will start a scratching motion, because the pinnae are extremely itchy in most infested dogs. However, the author has seen confirmed cases of scabies in which no pinnal-pedal reflex was present. In addition, the pinnal-pedal reflex can be found in dogs that have extreme pruritus from other disorders such as severe food allergy (adverse food reaction).

How is scabies diagnosed?:

The easiest diagnosis is when scabies mites, eggs, or scabies fecal pellets are found on skin scrapings. However, it is widely known among dermatologists that some dogs with scabies have relatively few mites even though their symptoms are severe. This may be due to the hypersensitivity (e.g. allergic tendency) of some dogs to the infestation. I.e., a small number of mites can cause severe disease in some individuals and it is a matter of chance that mites are picked up on skin scrapings (the main diagnostic test for skin mites).

What is done if mites are not found?

If the patient's history includes risk factors, many dermatologists will recommend treatment of scabies mites as both a diagnostic test and also a therapy. Risk factors include having wild or stray animals (especially but not limited to foxes) in the outdoor environment, other pruritic pets in the environment, history of problems developing soon after exposure to other dogs such as kennels, grooming establishments, or veterinary hospitals. If the patient's dermatologic examination reveals classic lesion locations including pinnal-pedal reflex (see above), lesions of the extremities including the elbows, hocks (ankles), treatment may be indicated. In addition, because the symptoms of scabies are almost exactly the same as severe allergies, many dermatologists recommend treatment for scabies as part of a routine workup for pets with significant itchiness (pruritus). All contact dogs, symptomatic or not, must be treated appropriately. Some dermatologists recommend treating cats in the home even if the cats do not have symptoms.

Treatment:

Fortunately, there are very effective treatments for scabies in veterinary medicine, perhaps even better than what is available for humans with scabies. The main pitfall of treating scabies is to make sure treatment is continued for an adequate period of time – it is important not to stop anti-parasite treatments too soon before all mites are eradicated on all pets. All pets must be treated whether they have symptoms or not. Treatment of the indoor environment may not be necessary. For the very itchy pet, some symptomatic therapy for the allergic sensitivity is indicated to give the pet some quick relief. This is a situation where the benefits of steroid therapy likely outweigh the risks. Treatment includes avermectin type antiparasite drugs (ivermectin, milbemycin, selamectin), topical lime-sulfur solution, and even topical amitraz.

Humans too:

Any humans with skin problems should be evaluated by a physician. Humans can get scabies from dogs, though likely not as easily as they can get scabies from other humans.

Cats and notoedric mange:

Although there are rare reports of finding Sarcoptes mites cats, it is believed that scabies mites are not able to live or complete their life cycle on cats. However, cats have a similar mange as sarcoptic mange of dogs. This is mange caused by Notoedres mites. These mites cause intense itchiness (pruritus) usually around the head of cats (perhaps because the cat cannot groom its head as effectively as the rest of its body). Notoedres can be treated sometimes with similar therapies as is used for dogs.

See also… Pet Skin Disease Info