Demodectic Mange in Dogs: Signs, Treatment and Recovery

Most dogs carry a small number of Demodex mites in their hair follicles and never show any sign of them. Demodectic mange, also called demodicosis or simply demodex, develops when these mites multiply far beyond their normal numbers. This usually happens because the dog's immune system is not keeping them in check.

It is a common skin disease, seen most often in puppies and young dogs. Many mild cases clear up on their own. Widespread cases need a vet's care, and treatment can take several months.

What causes it

The main mite in dogs is Demodex canis. A few rarer species have also been described. These mites live their whole life on the dog and cannot survive off it.

Puppies pick up the mites from their mother through close skin contact during nursing, in the first days of life. This is normal and usually causes no signs at all.

In young dogs, the disease is thought to be linked to an immune system that is still maturing, or to an inherited weakness in it. In adult dogs, it often points to another problem that has weakened the body's defenses. Examples include hormone diseases such as an underactive thyroid or an overactive adrenal gland, cancer, long courses of steroids or chemotherapy, and leishmaniosis, a parasite disease spread by sand flies. Severe stress, poor nutrition and intestinal worms can also play a part. In many dogs, no single cause is ever found.

Signs to watch for

Vets describe two main forms. The localized form shows up as one or a few small patches, usually on the face or front legs. It is most common in puppies under a year old. The generalized form covers large areas of the body, involves many patches, or affects the paws. It usually starts in young dogs and is less common in adults.

• Patches of thin hair or bald spots, often around the eyes, lips or on the front legs
• Red, scaly or crusty skin in those areas
• Skin that turns darker or thicker over time
• Small bumps, blackheads or pimple-like spots
• Swollen, sore or hairless paws
• A greasy coat or an unpleasant smell from the skin

Itching is often mild or absent at first. It tends to increase if the skin becomes infected. This is one clue that separates demodex from sarcoptic mange, also called scabies, which is usually very itchy. Skin tests at the vet help tell the two apart.

When it is an emergency

A few small bald patches on an otherwise healthy puppy are worth a vet visit soon, although they do not need emergency care. Generalized demodicosis is more serious. When bacteria invade the damaged skin, a deep infection can develop and make the dog truly ill. In severe cases it can become life-threatening. It is best to call a vet the same day if you notice any of the following.

• Many pus-filled bumps, open sores or draining wounds
• Swollen, painful or bleeding skin, especially on the paws
• A strong, foul smell from the skin
• Fever, weakness, low energy or loss of appetite
• Swollen lymph nodes, felt as firm lumps under the jaw or behind the knees

How vets diagnose it

The usual first test is a deep skin scraping. A light scraping can miss the mites, because they sit deep inside the hair follicles. The vet gently squeezes a small patch of affected skin and scrapes until a tiny amount of blood appears, then checks the sample under a microscope. Finding more mites than a healthy dog would normally carry points to demodicosis.

In sensitive places such as the paws or around the eyes, the vet may pluck a few hairs and look at the roots instead. Tape samples and samples of pus can also show mites. A skin biopsy is sometimes needed, for example in breeds with very thick skin such as the Shar Pei.

When an adult dog develops demodex, the vet will usually look for a hidden illness. This can mean blood tests and other checks. For dogs from areas where leishmaniosis occurs, that may include a test for it.

How it is treated

Treatment depends on the form. Many puppies with the localized form heal without special treatment within about six to eight weeks. The vet may simply recheck the patches to make sure they are not spreading, and treat any skin infection.

Generalized mange needs treatment. Many vets now use oral or spot-on medicines from the isoxazoline group, the same drug family used for flea and tick control. Other antiparasitic medicines are also options. The vet chooses the product based on the dog's age, breed, weight and overall health, so it helps to mention any history of seizures. Some herding breeds, such as collies and Australian shepherds, can carry a gene change that makes certain older antiparasitic drugs risky, so the choice of product is best left to the vet.

Mild skin infections are often treated with medicated shampoos, and deep infections may need antibiotics. If an underlying illness is found, treating it is part of the plan. For unspayed females with the generalized form, vets often recommend spaying, because heat cycles can trigger a relapse.

Treatment usually lasts for months. The vet repeats skin scrapings about once a month. Current guidelines advise continuing until two scrapings in a row show no mites, and then for a few more weeks. Stopping too early is a common reason for relapse. A dog is usually considered cured when there is no relapse for 12 months after treatment ends.

Steroid creams and tablets are generally avoided in dogs with demodex, because they suppress the immune response and can let the mites spread. If your dog already takes a steroid for another condition, ask your vet before making any change. Home remedies are not recommended for this disease.

Other pets and people

Demodectic mange is not considered contagious. The mites that cause it are adapted to dogs and do not live on people, cats or other animals. Humans have their own Demodex species, which are different. Mites can pass between adult dogs during close contact, but this does not usually cause disease, because illness depends mostly on the dog's own immune system.

Littermates can be affected, since they share the same mother and often similar genes. If one puppy in a litter has generalized demodex, it makes sense to have its siblings checked.

Sarcoptic mange behaves differently. Those mites spread easily between dogs and can cause an itchy rash in people. That is one more reason to let a vet confirm which mite is involved.

Prevention and long-term care

Good general health is the best protection, because worms, poor diet and other illnesses can weaken the immune system. That means a balanced diet, regular deworming, routine vaccinations as your vet recommends, and prompt care for any other illness. Some vets also suggest year-round flea and tick protection with an isoxazoline product, which may lower the chance of the generalized form developing. Ask your vet whether this suits your dog.

The tendency toward generalized demodex is thought to run in families. For this reason, guidelines advise that severely affected dogs and their parents are not used for breeding.

After recovery, watch for new patches of hair loss, especially in the first year. Relapses most often appear a few months after treatment stops. A quick recheck at the first sign makes them easier to manage.

Rescued and newly adopted dogs

Dogs that have lived on the street can have several risk factors at once. Street life can bring stress, hunger, worms and untreated illness, and many young strays are at the age when demodex is most common. In the Balkans, leishmaniosis is another disease to keep in mind. It is common in dogs in Greece, present in North Macedonia, and reported less often in Bulgaria and Serbia. In an adult dog from these regions, a vet may want to rule it out when demodex appears.

At Paw Squadron, the first stops after every rescue are the vet and a bath. Each animal gets a checkup, deworming and treatment against fleas and other parasites. Before adoption, every animal also receives treatment, vaccinations and a microchip.

A move to a new home is a big change, and stress is one of the factors linked to demodex. A checkup with your own vet in the first weeks helps catch any skin problem early. If a young dog develops a few bald patches, it is worth having them checked. Ringworm and sarcoptic mange can look similar, and simple tests tell them apart. Localized demodex often settles with time and veterinary follow-up.

If you are thinking about adopting and have questions about a dog's health history, you can send an adoption inquiry. More pet-care guides are in PawPedia.