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Demodex mites in dogs

Demodex mite species are cigar-shaped, microscopic mites, which live in hair follicles. Dogs catch these mites from their mothers in the first few days of life. Most dogs will never experience any clinical signs associated with their presence. However, in some animals demodicosis can occur, where the number of mites present on the pet increases substantially, causing skin problems and hair loss.

This article was written by a FirstVet vet

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Signs of demodicosis

There are two main types of demodicosis:

  1. Localised demodicosis: usually seen in puppies and young dogs. It affects one specific area of the animal, for example, the face or head. Patches of hair loss, ‘black heads’, and some reddening of the skin are the most common signs.
  2. Generalised demodicosis: seen in both young and older dogs. It affects the whole body. This is a more serious condition. Signs include itching, skin infections, extensive hair loss, scabs and sores.


Causes of demodicosis

The reason that demodex mites live on most dogs without causing harm, whilst others are severely affected, is unclear. It may be to do with the species of demodex present, or the dog’s immune response to the mite. A normally functioning immune system usually keeps Demodex mite numbers well controlled. Cases of demodicosis are therefore more common in dogs with a suppressed immune system, or an underlying illness.


Diagnosis of demodicosis

The aim is to find the mite and identify it microscopically. Skin scrapings and hair plucks are used to do this. Any complicating factors, such as skin infections, will also need to be diagnosed. Typically, a swab of the affected area is taken and sent to a laboratory. 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 will therefore lead to erroneous test results. If an underlying condition is suspected then further tests, such as blood and urine analysis, will be undertaken to establish the problem.


Treatment of demodicosis

Localised demodicosis has a very good prognosis and will usually resolve without treatment. Generalised demodicosis does require treatment. In contrast to localised form, this can be a long, drawn out affair. Spot-on treatments and medicated washes can be used to help reduce mite numbers. Antibiotics and anti-inflammatories can be given for skin lesions. Follow up appointments with your vet will be required to assess the progress of the case.


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