Monday , 19 February 2018

Ask A Vet: Dealing with Demodex (mange)

Q: My Boxer Mix, Dexter, was scratching and losing hair in certain areas. Scratching was mostly on the upper side of his front legs and back hip area. The hair loss appears around the mouth and eyes, as well as patches on his back. I took him to the vet and was advised it is a parasite called Demodex or something like this. I was prescribed a liquid medicine in the form of drops on his neck and back, as well as antibiotics for 21 days. I have administered the medicine for just over two weeks now and his condition does not seem to be improving in fact, I’ve noticed more bald spots on the front neck section. I’ve already spent over 250$ on the meds and vet visit. Should it be taking this long to show improvement or is another visit to the vet necessary?

A: How old is Dexter? Demodectic mange in a puppy is a lot different than demodectic mange in an older adult dog, so it would help to know which is the case.

Demodectic mange is caused by a mite or a microscopic ectoparasite that infects the hair follicles. The most common mite of demodectic mange is called Demodex canis. All dogs raised normally by their mothers possess this mite as they are transferred from mother to pup during the first few days of life. Most dogs live in harmony with their mites, never experiencing any problems. However, if conditions change, and cause any kind of suppression of the dog’s immune system, the demodex mites may gain the upper hand and can cause serious skin issues.

Demodex may be caused by a weakened immune system.

Symptomatic demodectic mange occurs in two forms: a mild, or localized form and a severe, or generalized form. Dogs with mild demodex symptoms have patchy hair loss over small areas of the body (most frequently on the face and on the sides of chest, abdomen and legs). The areas usually aren’t itchy, red, or irritated. Demodex mite infestations are typically seen in puppies and young dogs less than two years old, which is usually due to their growing/immature immune systems.

The severe or generalized form of demodex leads to more hair loss over large portions of the body and the skin presents as bald, infected, odorous and scaly. Generalized demodectic mange often requires  treatment with either Ivermectin (anti-parasite medication), Milbemycin oxime (Interceptor) or multiple treatments of Advantage Multi (drops on the back of the neck) as well as treatment with antibiotics (for secondary skin infections).

Many young dog cases “outgrow” demodicosis on their own, without treatment. This is because the immune system develops, gets stronger, and keeps the demodex mite population in control. However some puppies need veterinary help to overcome the problem. Resolution of a localized demodex lesion should be at least partially apparent after one month, though total resolution can take up to three months.

If an adult dog breaks out with demodex, your vet will want to look for reasons why the immune system may be weakened. Possible reasons include: cancer, hormonal imbalances (thyroid, Cushing’s disease), prolonged corticosteroid use, or immune system changes due to old age.

Repeated skin scrapings at regular intervals may be used to monitor a dog’s response to treatment. Dogs with mild cases may simply be monitored for resolution of hair loss, without further skin scrapings.

If you find that Baxter’s lesions are increasing after one month’s time, it might be a good idea to return to the vet and discuss more effective treatment options.

Hope this helps,

Dr Lissa





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