Veterinarian parasite mite removes of the dog's skin

If you have never experienced the itching, hair loss and skin and ear infections associated with mites in dogs, consider yourself fortunate. Dogs can be infested with several different species of mites, all of which cause unpleasant symptoms that range from itching and discomfort, to severe skin infection secondary to the damage caused by these pests. And, in some cases, mites are transmissible between dogs, and even from dogs to humans, which poses a public health risk. Knowing what to look for and pursuing effective and safe treatment is critical to eliminating these tiny pests.

There are four mites typically seen in dogs. The first three are common, especially in young and malnourished or neglected canines. Keep reading for symptoms and treatment options.

Demodex Mites: Symptoms and Treatment

Demodecosis, or infestation with Demodex canis mites, is a common parasite of young or malnourished and neglected dogs. These mites are inhabitants of the hair follicle of all dogs and are passed from the bitch to her pups during nursing. Most dogs develop immunity to infection with Demodex mites, and the mites remain in the hair follicle without causing any symptoms. But when the dog’s immune system is compromised, either by immune suppression or poor nutrition, these mites can proliferate causing hair loss, thickening of the skin, and in some cases, infection with other organisms (Staphylococcus bacteria or Malassezia yeast). Affected dogs are not itchy, but secondary yeast or bacterial infection can itch.

For many years, treatment options have been confined to toxic amitraz dips, daily oral ivermectin for months, or creams for small lesions. Recently, a new generation of prescription flea and tick preventatives in the isoxazoline class have been found to be effective for Demodex mange, even though they are not labeled for this use. At the time of publication of this article, four options from this drug class are available: afoxolaner, sarolaner, lotilaner and fluralaner. These are oral medications, available from your veterinarian, that are very effective against mites.

Itchy dog

Sarcoptes Mites: Symptoms and Treatment

Sarcoptic mange, or scabies, is another type of mite infection that can affect dogs and can also be transmitted to humans. This infection is caused by Sarcoptic scabiei mites that burrow in the skin, which leads to intense itching, hair loss, and secondary skin infections. It is transmitted from an infected dog to others that are in close proximity. Symptoms other than itching include red, scaly skin, starting in areas of thin hair, such as in the armpits and groin. Diagnosis is confirmed when these mites are seen on a skin scrape, but because they burrow so deep, skin scrapes from positive animals are rarely positive. Two products have been used for many years as treatment: selamectin (flea and tick preventative) given every two weeks instead of monthly, or imidacloprid/moxidectin administered monthly. The isoxazoline class (discussed previously) is also effective against scabies with monthly administration.

Dog with itchy ears

Ear Mites: Symptoms and Treatment

Infection with ear mites, or Otodectes cynotis, is generally seen in puppies, but can also occur in older dogs exposed to outdoor cats. These pesky mites are extremely itchy and cause a copious amount of black, dry debris. The excessive itching and head shaking can lead to rupture of blood vessels in the ear, causing marked swelling and pain. Fortunately, these mites are easily treated with prescription drops or with monthly application of selamectin for heartworm and flea prevention. Diagnosis is easily accomplished by looking at a sample of the debris under the microscope. If an infection is diagnosed, the treatment will likely need to be repeated, as these mites have a three-week reproductive cycle. All bedding should be processed through a washing machine and dryer to kill the larval stages.

Cheyletiella Mites: Symptoms and Treatment

Cheyletiellosis, or walking dandruff, is an infection with a mite (Cheyletiella yasguri in dogs) that lives its entire life cycle on the dog. These mites appear like dandruff flakes but can be seen to move on the fur. They are very itchy, and their bites can cause a rash characterized by small red splotches on the skin. Bathing will reduce the number of mites but does not eliminate infection. Diagnosis is accomplished by using a piece of tape to collect flakes and examining under a microscope to identify them. There is no labeled treatment for these mites, but repeated application of selamectin every two weeks for three treatments will eliminate all life stages of the mites. Pyrethrin shampoos or lime sulfur dips every week for three treatments are also effective.

As you can see, mites cause significant symptoms and can lead to more severe infection due to the damage of the skin or ears. Diagnosis can be tricky since the mites are not always captured on a skin scrape, and in the case of cheyletiellosis, a tape preparation is required for diagnosis. In other words, your veterinarian has to be looking for these pests. Fortunately, the isoxazoline class of oral flea and tick products will eliminate sarcoptic and demodectic mange. Consult your veterinarian if your dog is itching or has evidence of skin infection.

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Dr. Catharine Hennessy