Demodectic Mange (Demodex) in Dogs: Signs, Causes and Treatment

Here's the surprising thing about demodectic mange. The mites that cause it are already living on your dog. Healthy dogs carry a handful of them from puppyhood, and they never cause a problem.

So when demodex flares up, the real question isn't "where did my dog catch it?" It's "why can't my dog's body keep it in check?" That shift in thinking explains the treatment, the outlook and why it isn't contagious like sarcoptic mange.

What is demodectic mange?

Demodectic mange (demodicosis) is a skin disease caused by Demodex mites. The main species in dogs is Demodex canis. These cigar-shaped mites live inside the hair follicles and oil glands, where they feed on skin oils and dead cells.

A mother dog passes a few mites to her puppies during nursing, in the first days of life. From then on, the mites are part of your dog's normal skin community, a bit like the bacteria in your gut. Trouble starts only when the mite numbers explode.

You may see it called "red mange" or "puppy mange." The medical term is demodicosis. Mange from this cause is a different disease from the scabies-type mite. If you want a side-by-side comparison, our guide to mange in dogs covers both.

Why does demodex get out of control?

The immune system normally keeps the mites in balance. When it falters, they multiply, and the skin reacts.

Young dogs

Puppies have immature immune systems. That's why most cases appear in dogs under 12 to 18 months old, often between 3 and 12 months. For most, the immune system catches up with time. Some breeds are at higher risk, and the tendency runs in families. Pugs, Bulldogs, French Bulldogs, Boston Terriers, Shar-Peis, Dobermans, Dachshunds and Chihuahuas often appear on lists. For more on young dogs, see mange in puppies.

Adult dogs

When a healthy adult develops generalized demodex for the first time, vets look for a cause. Illnesses that weaken immunity include Cushing's disease, hypothyroidism, diabetes and cancer. Medications such as long-term steroids and chemotherapy also suppress immunity. Malnutrition and heavy stress can play a part. Adult-onset demodectic mange is a reason to investigate your dog's overall health, not just its skin.

Old dogs

Immunity declines with age. Senior dogs can develop demodex as part of that decline, or because of another illness.

Signs of demodectic mange

The look depends on how widespread the disease is. Vets divide it into localized and generalized forms.

Localized demodectic mange

Localized mange is the milder form, mostly seen in puppies under a year old. It causes one to five small, well-defined patches of hair loss, redness and scaling. Common sites are the face, around the lips and eyes, and the front legs. The patches can look like a moth-eaten spot or a ring.

There's usually little or no itching. Many cases clear by themselves as the puppy's immune system matures. A small percentage can progress to the generalized form, so your vet will want to keep an eye on it.

Generalized demodectic mange

Generalized mange covers many areas or whole regions of the body, or affects the paws (called pododemodicosis). The signs are more severe:

• Widespread hair loss and thinning fur
• Red, thickened or darkened skin
• Greasy scale, crusts and a musty smell
• Pustules, draining tracts and sore, swollen paws
• Swollen lymph nodes and, in bad cases, fever and lethargy

Secondary bacterial infection is common and is what makes many dogs itchy and sore. Generalized disease can be a long fight, so early veterinary care matters.

Demodex mites in a "normal" dog

Finding a few demodex mites on a skin scraping doesn't mean a dog has mange. Healthy dogs carry them. The vet looks for an unusually high number, together with the clinical signs.

Demodex or sarcoptic mange: how to tell them apart

Owners often can't tell the two apart at home, and that's fine. Both cause hair loss. The details differ, though, and they matter because only one spreads.

Demodex tends to start on the face and front legs of a young dog, with bald patches and little scratching. Sarcoptic mange tends to start on the ear edges, elbows and belly, with frantic itching that comes on fast. A puppy with a bald, scaly patch around one eye and a happy, non-scratching attitude is much more likely to have demodex. A dog that scratches all night and has crusty ear tips is a scabies suspect.

Both can occur together, and both can lead to bacterial infection. Only a skin scraping settles it. If anyone in your home is itchy, tell your vet, because that points to sarcoptes.

What it feels like for your dog

Localized demodex rarely hurts. Generalized demodex, with infected, swollen paws and widespread sores, can be painful, and affected dogs may limp, lick their feet and go off their food. Think of the difference between a sunburned patch and an infected blister. Both need care, but one is much more miserable than the other.

Feeding and lifestyle

There's no special diet that cures demodex. But a complete, balanced food suited to your dog's age supports the immune system. Puppies need puppy food for large or small breeds as appropriate. Keep vaccinations and deworming on schedule, because a puppy with worms or other illness has less energy left over to fight mites. Avoid unnecessary steroid products unless your vet prescribes them, since steroids can lower immunity and let mites multiply.

How vets diagnose demodex

The standard test is a deep skin scraping. The vet squeezes a fold of skin and scrapes with a blade until a little blood appears, because the mites live deep in the follicles. They look at the sample under a microscope, counting mites, eggs and larvae. Plucked hairs (trichogram) and skin biopsies can also help.

A vet will also check for other causes, including fungal infection, bacterial infection, allergies and hormone disease. In adults with generalized disease, expect blood and urine tests to look for the reason the immune system is weak.

Demodectic mange treatment

Treatment depends on the form and your dog's health.

Localized cases

Many localized cases need only monitoring, with rechecks every few weeks. Some vets prescribe a mild topical treatment to speed recovery. Healthy puppies often clear within 1 to 2 months without strong drugs.

Generalized cases

Generalized mange needs anti-mite medication for months. Isoxazoline medicines (the same family as many monthly flea and tick chews, such as afoxolaner, fluralaner and sarolaner) are now often the first choice. Macrocyclic lactones such as milbemycin oxime and moxidectin are also used. Treatment continues until at least two skin scrapings in a row, taken a month apart, are negative. Many dogs need several months of medication.

Treating infections and skin

Antibiotics treat secondary bacterial infection. Medicated shampoos, such as benzoyl peroxide, can help flush follicles and calm the skin. Always follow your vet's advice about bathing, because the wrong shampoo can strip the skin.

Medicine safety

Some breeds, including Collies, Shetland Sheepdogs and Australian Shepherds, can carry a gene change (MDR1) that makes certain drugs, such as ivermectin, dangerous. Your vet may test for it first. Never use a product intended for another animal without checking.

Recovery and relapses

Treatment can feel slow. The first sign of progress is that the skin calms down and the smell fades, then hair begins to regrow. Fully regrown fur may take a couple of months.

Relapses can happen, especially before a dog is about 12 to 18 months old. If bald patches return, call your vet quickly. Keep every recheck, because stopping medicine on the day the skin looks better is how many relapses start.

Dogs with a history of generalized demodex shouldn't be bred, because the tendency is inherited. Many vets also recommend neutering or spaying, since heat cycles can bring on relapses.

Living with a dog that has had demodex

Once your dog has cleared the mites, life returns to normal. Keep a quick routine going for the next year. Check the skin monthly for new bald or scaly patches, especially around the eyes, lips and paws. Take a photo each time so you can spot slow changes. Book a recheck if you notice anything, rather than waiting to see if it passes.

Tell any new vet or groomer about the history. Long-term steroid use should be a considered decision for a dog with a past of generalized disease. If your dog needs surgery or another illness comes along, a weakened immune system can bring demodex back, and early treatment keeps it small.

Caring for your dog at home

You can't cure demodex with home remedies, but you can help recovery.

• Give every dose on time and finish the course
• Feed a balanced diet and keep your dog at a healthy weight
• Keep bedding clean and the skin dry
• Use a soft cone if your dog is chewing sore paws
• Reduce stress where possible, since it can weaken the immune system
• Keep flea and tick prevention up to date

Don't use olive oil, borax or other online remedies. They don't kill follicle mites and can irritate the skin.

Questions owners often ask

Owners often ask whether to keep other pets away. You don't need to, because demodex isn't passed on as an infection. Another common question is whether a mite-free dog can relapse. It can, mostly in the first year or two, so keep your rechecks. Some owners also worry about their own skin. People have their own harmless Demodex species, and it isn't the one from your dog.

When to see a vet

See a vet when you notice bald, scaly or red patches, especially in a puppy, and don't wait for them to spread. Early treatment shortens recovery.

Go the same day if your dog has:

• Painful, swollen paws or pus-filled sores
• Fever, lethargy or refusal to eat
• Widespread hair loss that's getting worse
• Sudden mange as an adult dog with no history

For itchier skin problems, see hot spots on dogs, and for more guides visit our skin and coat hub.