Demodex and Sarcoptic Mange (Scabies) in Dogs and Cats

The truth about dogs and cats...and mange - an exclusive by our Pet Doc.

Does Your Dog or Cat Have Mange?

"Doc, I think my dog's got mange. Do you think we can treat or is too late?" This is how a conversation once started when I entered an exam room to see a dog that was "bald all over and chewing hair out". Growing up in and starting my veterinary career in south central Texas made me no stranger to itchy dogs and cats. We have allergies and parasites galore down there and of all the common and relatively benign disease processes I see, mange is one of the most misunderstood.

What is Mange?

First of all, the term mange is used to describe a skin disease that is caused by a parasite, or mange mite. There are two types of commonly diagnosed mange mites, demodex and sarcoptic. The first, and most common in my practice, is called Demodectic mange or demodicosis. The term demodex is commonly used to describe this as well.

Demodex Mange

Demodex mange of the dog is caused by the mite Demodex canis. This mite is a normal inhabitant of the canine skin. Problems oocur when there is an overpopulation of these mites. Demodectic mange is not contagious. The problem can either occur in a localized area such as the muzzle or feet or can be a generalized problem. Manifestation of the disease can include hair loss, pustules, itchy skin, and crusty lesions over the affected area. Demodectic mange can be diagnosed by skin scrapings.

Demodex Mange is the Result of Another Problem

The thing to know about demodectic mange is that it is a secondary problem. Predisposing conditions could include anything that compromises the animal's immune system. Puppies that are diagnosed with the disease simply do not have the immunity that older more mature dogs have. Adult onset demodicosis warrants a thorough investigation into predisposing factors that may include hypothyroidism, hyperadrenocorticism, and many others.

Demodex Mange in Cats

Feline demodicosis can also be localized or generalized in appearance with many of the same manifestations as canine demodicosis. Any cat that is diagnosed with demodectic mange should be tested for underlying illnesses that may include feline aids, leukemia, diabetes and many others. More recently I have seen cats with localized demodicosis of the external ear canals. These cats were both FIV positive.

How to Treat Mange in Dogs and Cats?

Treatments for both dogs and cats may include regularly scheduled medicated baths and dips or alternative oral medications depending on your veterinarians assessment and preference. The treatment of demodectic mange is typically more a nuisance than it is a problem. The treatments can be costly over a period of weeks, and as long as there is no underlying illness you can expect your pet to be no worse for having the problem. Beware of "home remedies" when it comes to treatment of demodectic mange. There are lots of recommendations of home remedies for mange that become far more serious problems than the initial problem of demodicosis. Animals that are diagnosed with demodectic mange should not be used for breeding as this is an inheritable disease.

Sarcoptic Mange (Scabies)

The second type of commonly diagnosed mange can affect dogs, cats, pocket pets, and can even be zoonotic, or transmitted to humans. Sarcoptic mange or scabies is also caused by mites.

Symptoms and Treatment of Sarcoptic Mange in Dogs and Cats

Canine scabies is caused by Sarcoptes scabiei and feline scabies is caused by Notoedres cati. Animals affected by scabies typically present with uncontrollable itching. Skin lesions may appear as thick crusts, bleeding scabs, or even oily discharge. Diagnosis can be made by doing a skin scraping. There are many false negative tests when scraping for scabies and often this diagnosis is made by exclusion or therapeutic trial. Canine scabies is extremely contagious between dogs and can also be spread to humans and other animals. Many diagnoses of scabies are accompanied by the owner complaining of being itchy as well. Feline scabies is also extremely contagious between cats and is also a zoonotic disease. Much like demodectic mange, the treatment of canine and feline scabies is typically very successful and carries a good prognosis. 

- Jacob Mireles, D.V.M, aka The Pet Doc