Demodectic mange, or demodicosis, is a skin disease caused by Demodex mites. Healthy dogs carry a few of these mites in their hair follicles, and less often in the oil glands of the skin, without any problem [1]. Disease starts when the mites multiply to large numbers inside the follicles, which leads to inflamed skin and hair loss [1].
See your vet about patchy hair loss or red, scaly skin. The generalized form is a serious condition that needs veterinary treatment [1].
For other causes of hair loss, see hair loss in dogs. For the other common mange of dogs, see sarcoptic mange in dogs.
Is it contagious?
Demodicosis caused by the common dog mite, Demodex canis, is not regarded as a contagious disease [1]. Puppies pick up the mites from their mother in the first few days of nursing, and the mites then stay on as part of the normal skin life [1].
Why some dogs get it
Experts do not yet fully understand why the mites get out of control in some dogs [1]. Two factors stand out:
- Genes. The juvenile form runs in families. Some parent dogs produce affected puppies in litter after litter, and some breeds are affected more often [1].
- The immune system. A weak or faulty immune response to the mites seems to let them multiply. The mites themselves and a secondary skin infection may also dampen the skin’s defences [1].
The forms of demodectic mange
Vets sort the disease by how much of the body it covers (localized or generalized) and by the age at which it first appears (juvenile-onset or adult-onset) [1].
Localized demodicosis
- Who: mostly dogs under 1 year old [1].
- Signs: one or a few patches of hair loss with scaling, redness or darker skin, often around the eyes, the corners of the mouth, the head and the front legs [1]. Itching is not typical unless a bacterial infection sets in [1].
- Course: most cases clear up by themselves, but a small share go on to the generalized form [1].
Generalized demodicosis
Signs of generalized disease include many patches spread over the body, a whole body region such as the face being involved, or two or more paws being affected [1].
- Juvenile-onset: it usually starts as a few patches that spread, most often in young dogs, and these dogs seem to have an inherited tendency [1]. Few of them get better without treatment [1].
- Adult-onset: dogs that first get the disease at about 4 years of age or older are said to have adult-onset demodicosis [1]. It is usually linked to another illness, such as Cushing’s disease, an underactive thyroid or cancer, or to long-term medicines that suppress the immune system [1]. In some dogs no other illness is found at first, so vets keep a close watch, because one can show up later during treatment [1].
Signs of generalized demodicosis
The signs vary a lot from dog to dog [1]. They can include:
- patchy or widespread hair loss with red, scaly skin and darkened skin [1];
- bumps, pimples, blackheads and greasy skin [1];
- bacterial skin infection, which is common and can be shallow or deep, with crusts and draining sores [1];
- sore, infected paws. Your vet will check any dog with paw inflammation for these mites [1]. For deep infections between the toes, see interdigital furunculosis in dogs;
- in more severe cases, swollen lymph nodes, fever, tiredness and poor appetite [1].
How vets diagnose it
Vets usually confirm the diagnosis by looking at deep skin scrapings under a microscope [1]. In dogs with demodicosis they often find many mites at different life stages [1]. On the face and paws, where scraping is hard, the vet may pull a few hairs and look at those instead [1]. A skin biopsy is rarely needed [1].
For dogs that develop the disease as adults, your vet will also run tests to look for an underlying illness [1].
Treatment
Your vet chooses the treatment and rechecks your dog. In general terms [1]:
- the localized form often needs no mite treatment, because most cases clear up on their own. Your vet decides whether your dog needs treatment;
- the generalized form needs treatment prescribed by your vet;
- a bacterial skin infection may need its own treatment, chosen by your vet;
- your vet repeats skin scrapings at rechecks to follow the number of mites, and keeps checking for a while after they disappear before calling the dog cured;
- in adult-onset disease, your vet looks for the underlying illness and treats it;
- medicines that suppress the immune system should be avoided in dogs with demodicosis.
At home, as directed by a vet:
- give every treatment exactly as your vet prescribes, and do not stop early;
- tell your vet about every medicine your dog takes;
- go back for every recheck and skin scraping.
On breeding: dogs with juvenile-onset generalized demodicosis pass on the tendency to their puppies, so they should not be used for breeding [1].
Outlook
Outcomes vary between forms [1]:
- Localized: most cases clear up without treatment.
- Generalized: treatment often takes several months and many vet visits. Dogs with an underlying illness that cannot be cured may need lifelong care.
- Coming back: the disease can come back, especially when treatment is stopped too soon or rechecks are missed.
These are statements about groups of dogs. They cannot predict how one dog will do. Your vet can explain what this means for your dog.
When to see your vet
See your vet if your dog has:
- patches that are hairless, red and scaly [1];
- hair loss over large areas of the body [1];
- red skin, darkened skin, pimples, blackheads or crusts [1];
- sore or swollen paws [1];
- draining sores, swollen lymph nodes, tiredness or fever [1].
FAQ
Can my other pets or my family catch it?
Demodicosis caused by the common dog mite is not regarded as contagious [1]. All dogs carry a few of these mites [1].
Will localized mange go away on its own?
Most cases do, but a small share spread and become generalized [1]. Your vet confirms the diagnosis and decides on treatment.
Why is my vet testing for other diseases?
When demodicosis first appears in an adult dog, it is usually linked to another illness that weakens the immune system [1], so your vet looks for one.
The bottom line
All dogs carry a few Demodex mites. Demodectic mange happens when the mites multiply to large numbers in the hair follicles. The localized form mostly affects dogs under 1 year old and usually clears up by itself. The generalized form is serious and needs veterinary treatment, and when it starts in an adult dog it is usually linked to another illness. The disease is not regarded as contagious. Your vet confirms it with skin scrapings, chooses the treatment and rechecks your dog.
This article is for general information only and does not replace advice from your veterinarian. If your dog has patchy hair loss or red, scaly skin, see your vet.
Sources
- Torres SMF, et al. 3.1 Canine Demodicosis. Small and Large Animal Dermatology Handbook, Vol. 1. University of Minnesota Libraries Publishing, 2025 (CC BY 4.0). https://open.lib.umn.edu/animaldermatology/chapter/canine-demodicosis-new/