EAR MITES

Ear mites are tiny infectious organisms resembling microscopic ticks. The mite can just barely be seen as a small white dot, but usually must be detected by examination of a sample of ear debris under a microscope. Infection usually produces a characteristic dry black ear discharge commonly said to resemble coffee grounds. The discharge is composed of ear wax, blood, inflammatory biochemicals, and ear mites themselves. Most ear mite cases are found in cats, but ear mites can infect dogs.

The mite lives on the surface of the ear canal skin, though sometimes migrates out onto the face and head of its host. Eggs are laid and hatch after 4 days of incubation. The larva hatches from the egg, feeds on ear wax and skin oils for about a week and then molts into a “protonymph,” which in turn molts into a “deutonymph.” The deutonymph mates with the adult male.

After mating, the deutonymph molts into either an adult male or an adult female. If she becomes a female, she will be pregnant with eggs as a result of the mating. If he develops into a male, there are no consequences to the mating and he is ready to mate with deutonymphs of his own choosing. The adult mite lives approximately two months. The life cycle (the time it takes for an egg to develop into an adult mite ready for parenthood) requires 3 weeks.

Ear mites readily transmit from host to host by physical contact. Ear mites came from some other animal with whom your pet has been in contact with. Because mites are easily transmissible by physical contact, treatment for mites often must include all household pets.



Ear mites in a cat's ear canal

The presence of the mites is very inflammatory and can generate very irritating ear infections. Skin disease can also result from infection by the ear mite. Mites stimulate the wax-producing glands inside the ear. The buildup of wax can then cause inflammation and lead to even more discomfort for the cat.

If left untreated ear mites can cause a bacterial and yeast infections and, in extreme cases, rupture of the ear drum. Ear mites (Otodectes cynotis) are the most common cause of outer-ear inflammation in cats - especially kittens and young cats. Frequent ear scratching and head shaking are the most often seen symptoms. When a mite-infested cat constantly scratches its ear, it can tear open tiny blood vessels in the ear flap, which can lead to swelling (known as hematoma) and permanent disfigurement.


Ear mite infection is contagious among cats and dogs. Typically, the most common incidence is in outdoor cats. Mites infestations can sometimes be persistent. In a multicat household, for example, an asymptomatic cat with mites could repeatedly re-infect a recently treated cat. So all cats and dogs in a household would need to be treated. Humans have been reported to develop skin rashes in rare cases, but the human pet owner is extremely unlikely to experience any symptoms when their pet is infected with ear mites.



A veterinarian can suspect that a cat has ear mites if the cat is young, its ears are full of the wax, and the insides of its ears have an unpleasant odor. However, to confirm the diagnosis, your veterinarian will probably inspect the inside of your cat's ears with a magnifying otoscope, Med-Rx videoscope, or visualization with the aid of a microscope. The warmth from the light of an otoscope draws the mites out from the ear wax and causes them to move about on the dark surface of the wax where they're relatively easy to spot.

After cleaning the ears, vets typically treat mites with medication, usually in the form of drops, that not only kill the parasites but also prevent secondary infections and reduce inflammation. For treatments other than single dose treatments, it is imperative to continue using the medication at home for the recommended duration to cover the complete 3 week life cycle of the ear mite. If treatment is stopped too soon (for example, when the cat stops scratching) developing mites will reach adulthood and multiply. Whatever ear mite treatment is used, re-examination by your veterinarian is essential.

TOPICAL TREATMENTS: AT LEAST THREE WEEKS USAGE

There are numerous products available for ear mite eradication. Most older and over-the-counter products contain insecticides which do not kill incubating mite eggs. Because of this limitation, such products must be used for at least the duration of the 21 day life cycle of the mite. Some specialists recommend a 30 day treatment course with such products.

TOPICAL TREATMENTS: AT LEAST TEN DAYS USAGE

Another approach involves the use of a topical ear product called Tresaderm® (Merial) which contains an antibiotic for any secondary bacterial infections, a cortisone derivative for the inflammation, and thiabendazole to kill yeasts and mites. This product is able to kill the developing mite eggs. This cuts the treatment course down to 10-14 days and provides an oily lubricant with which to clean the ears..

INJECTION: TWO TO FOUR TREATMENTS

A newer, but not FDA-approved treatment, involves the use of Ivermectin, a powerful anti-parasite medication. Ivermectin is especially helpful for pets who will not allow direct treatment of their ears. Most Ivermectin injectable protocols involve shots weekly or every two weeks. This is a highly effective method of ear mite eradication but there are some limitations. Certain breeds of dogs are sensitive to this medication and cannot receive this treatment. Certain individual pets have similar sensitivities which cannot be predicted by breed.

SINGLE USE PRODUCTS

There are currently several prescription products available that reliably eradicate ear mite infections with one single use. Two such products are available for use directly in the infected ear: Acarexx, a topical version of Ivermectin, and Milbemite, a topical version of Milbemycin Oxime, the same active ingredient as in the heartworm preventive Interceptor. These products are approved for cats only and are available only through veterinarians.


Acarexx is a highly effective ear mite treatment that is applied to the ear cana after cleaningl. It kills adult ear mites and their eggs. The benefits are that it only requires one application, is well-tolerated by cats, and is very effective.


Another topical product now available against ear mites is Revolution® (selamectin). A single application is used on the skin, the product is absorbed into the body where it kills numerous other parasites and then returns to be concentrated in the skin. Revolution® is primarily a flea control product but is approved for both dogs and cats for the treatment of ear mite infection. Continuing use of Revolution® for flea control has the added benefit of preventing further ear mite infections (especially helpful for outdoor cats). While Revolution® use will kill the mites, ear cleaning is needed at the beginning of therapy (and possibly at the end) to remove the irritating wax and debris. Your pet’s ears should be re-checked for ear mites according to your veterinarian’s recommendations.

Here are some things to consider if your pet’s ear mite infection has not gone away:

1. Was the mite infection confirmed initially? Remember, it is easy to be misdirected by the presence of a discharge that appears “mite typical..” Were mites seen in the ear debris under a microscope?
   
   
2. Has the mite infection been confirmed after therapy? Are ear mites still present after treatment? Sometimes, debris from the ear mite infection can still cause discomfort if not thoroughly removed from the ear canal. Sometimes a bacterial infection remains although the mites are gone.
   
   
3. Were all the hosts in the family treated? If all pets were not treated, begin again this time including all pets in the protocol.
   
   
4. Consider using one of the newer products in production.
   
   

*Do not make the diagnosis of ear mite infection yourself. If you think your pet has an ear infection, see your veterinarian for proper evaluation rather than using an over-the-counter remedy.

The best method of ear mite prevention is to eliminate exposure to affected cats. Check your cats’ ears several times weekly and clean them as often as needed. Always clean the ear very gently to prevent trauma to a diseased ear drum.