Why is My Dog Losing Hair? What You Need to Know About Demodectic Mange

Estimated Reading Time 3 minutes
Why is My Dog Losing Hair?  What You Need to Know About Demodectic Mange

Demodectic mange, also known as demodicosis or “red mange”, is caused by a cigar-shaped, microscopic mite called Demodex canis. These mites are transmitted from mother to pup within the first few days of life. They live deep within the hair follicle and cannot be transmitted to other healthy dogs or humans. Most dogs have such low numbers of demodex mites on their skin that they never experience problems. However, demodicosis can develop when these mites occur in higher numbers, causing skin problems and hair loss.

Are you concerned about your pet?

Book a video consultation with an experienced veterinarian within minutes.

  • Professional vet advice online
  • Low-cost video vet consultations
  • Open 24 hours a day, 365 days a year

Signs of Demodex in Dogs

There are two main types of demodicosis:

1. Localized demodicosis: usually seen in puppies and young dogs.

This mild infection occurs in one specific area of the animal, such as the face or head. Patches of hair loss, “black heads”, and some reddening of the skin are the most common signs.

2. Generalized demodicosis: seen in both young and older dogs.

This is a more serious condition, affecting the whole body. Signs include itching, extensive hair loss, scabs, sores, and secondary infections.

Causes of Demodicosis in Dogs

Demodex canis may be the most common type of mange mite in dogs, but it remains unclear why some are more severely affected than others. Demodicosis seems to occur primarily in dogs with immature or suppressed immune systems resulting from underlying illness or administration of certain medications. A weakened immune response allows the mites to rapidly increase in number, while a well-functioning immune system is typically able to keep Demodex numbers controlled.

Diagnosis of Demodex mites in Dogs

Because Demodex mites are microscopic, your veterinarian will need to collect deep skin scrapings and hair plucks from your dog. These samples will be evaluated under a microscope to confirm the diagnosis.

Any complicating factors, such as skin infections, will also need to be diagnosed. Typically, a swab of the affected area is taken and either evaluated under the microscope or sent out to a laboratory for bacterial culture. It is important not to use any antibacterial agents or creams on the affected area of skin for 24 hours before your dog is seen by the vet. These substances affect the bacteria present and can lead to inaccurate test results.

If an underlying condition or illness is suspected, further testing may be necessary. Your veterinarian may recommend certain blood tests or other lab work to better diagnose the problem.

Treatment of Demodicosis in Dogs

Localized demodicosis has a very good prognosis. These mild infections usually resolve with topical treatment. Some cases resolve with no treatment at all.

In contrast, generalized demodicosis may require a long, or multi-faceted treatment process. Spot-on treatments and medicated baths or dips can be used to help reduce mite numbers. Certain oral medications, such as antiparasitics, antibiotics, and anti-inflammatories, may also be necessary.

Follow-up appointments with your veterinarian will be needed to assess the progress of the case.

Read more:

Symptoms and Treatment of Mites in Dogs

Ear Mites in Dogs

Flea Prevention and Control for Dogs

Need to speak with a veterinarian regarding your dog's hair loss or another condition?

Click here to schedule a video consult to speak to one of our vets. You can also download the FirstVet app from the Apple App Store and Google Play Stores.

Published: 8/11/2020
Last updated: 10/27/2021

Are you concerned about your pet?

Book a video consultation with an experienced veterinarian within minutes.

Get started
  • Low-cost video vet consultations, 24 hours a day Low-cost video vet consultations, 24 hours a day
  • Experienced, licensed vets Experienced, licensed vets
  • Over 700,000 satisfied pet owners Over 700,000 satisfied pet owners
Low cost consultations, 24 hours a day.Low cost consultations, 24 hours a day.

With FirstVet, the vet clinic and pet shop are only one tap away. Get fast advice, trusted care and the right pet supplies – every day, all year round.


FirstVet Inc

900 3rd Ave 29th Floor


New York