|
EAR MITES IN DOGS
|
|
THE PET HEALTH LIBRARY
Answering
Your Questions About Ear Mites (Otodectes cynotis)
What Are Ear Mites?
Ear mites are tiny infectious organisms resembling microscopic ticks.
The mite can just barely be seen as
a small white dot with the naked eye, but it usually must be detected
by examination of a sample of ear wax under a microscope. Infection usually
produces a characteristic dry black ear discharge commonly said to resemble
coffee grounds. Because of the classical appearance of this discharge, infection
is often diagnosed based on the presence of such discharge though without
visual confirmation of the mite under the microscope, it is possible to
be led astray. The discharge is composed of ear wax, blood, inflammatory
biochemicals, and ear mites themselves.
The Bizarre Ear Mite Life Cycle
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.
What seems especially bizarre to us mammals is that the deutonymph has
not yet developed a gender at the time it 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 gravid 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 2 months happily eating ear wax and skin
oils. The life cycle (the time it takes for an egg to develop into an adult
mite ready for parenthood) requires 3 weeks.
Most ear mite cases are found in cats. Dogs can be infected as well
but since dogs more commonly get ear infections of other types, ear infections
in dogs rarely involve mites.
How Did My Pet Get Ear Mites?
Ear mites readily transmit from host to host by physical contact. Ear
mites came from some other animal with whom your pet has been socializing.
Because mites are easily transmissible by physical contact, treatment for
mites often must include all household pets.
What Harm Comes from Ear Mite Infection?
The presence of the mites is inflammatory and can generate very irritating
ear infections. Skin disease can also result from infection by the ear mite.
Is This Contagious?
Ear mite infection is certainly contagious among cats and dogs. Typically,
the victim is an outdoor cat. Humans have been reported to develop skin
rashes rarely; in general, we may consider that a human pet owner is extremely
unlikely to experience any symptoms when their pet is infected with ear mites.
How Do I Get Rid Of Ear Mites?
Topical Treatments: At Least 3 Weeks Usage
There are numerous products available for ear mite eradication. Most
older and over-the-counter products
contain insecticides that 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 10 Days Usage
Another approach involves
the use of a topical ear product called Tresaderm® (manufactured by
Merial) that contains an antibiotic for any secondary bacterial infections,
a cortisone derivative for the inflammation, and thiabendazole to kill
yeasts and mites. This is an excellent ear product and is able to kill
the developing mite eggs. This cuts the treatment course down to 10 to 14
days and provides an excellent oily lubricant with which to clean the ears
as well. This product has been favored by veterinarians for decades.
Injection: Two to Four Treatments
A newer treatment that is not FDA-approved 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 2 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 take it. Certain individuals
have similar sensitivities which cannot be predicted by breed. Injectable
ivermectin is not approved for the treatment of ear mites in small animals.
See more detail on the use of ivermectin.
Another product that has been popular is fipronil, the active ingredient
in the flea control product Frontline.
While Frontline is not helpful against ear mites when used on the skin
as directed for fleas, it is effective when used topically in the ear. This
use is also not sanctioned by the manufacturer and possible adverse effects
from the product’s use in this way have not been formally studied.
See general information on Frontline.
Single Use Products
There are currently several prescription products available that reliably
eradicate an ear mite infection 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.
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). It is important to realize
that Revolution® is a prescription medication and cannot be obtained
without proper veterinary evaluation. Revolution for Cats
Further, 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. Be sure to have the ears re-checked according
to your vet’s recommendations.
Success will not be met unless the ear canal is thoroughly cleaned.
This is true whether a topical solution or one the systemic products is
used.
See general information on Revolution® from
the manufacturer.
Success will not be met unless the ear canal is thoroughly cleaned.
This is true whether a topical solution or one the systemic products is
used.
What if They Just Don’t
Seem to Ever Go Away?
Occasionally, we receive messages regarding a case of ear mites
for which “everything” has been used and the mites simply will not go away.
In this situation consider the following tips:
Was the mite infection confirmed initially? Remember, it is easy to
be fooled by the presence of a discharge that appears “mite typical.”
Has the mite infection been confirmed after therapy? Sometimes, a telltale
hard bit of ear wax must be removed from the ear before comfort is finally
achieved. Sometimes a bacterial infection remains though the mites are long
gone. Treating for ear mites when none are present will not achieve results.
Were all the hosts in the family treated? If all pets were not treated,
begin again this time including all pets in the protocol.
Consider using one of the new products.
Do not make the diagnosis of ear mite infection yourself. If you think
your pet has an ear infection, see the vet for proper evaluation rather
jumping straight to an over-the-counter remedy. You will need the right diagnosis
before you can intelligently choose an ear treatment product.
This work was originally published by Veterinary Information
Network, Inc. (VIN) and is republished with VIN's permission.
Copyright
2004 - 2007 by the Veterinary Information Network, Inc. All rights reserved.
The above information is simply informational.
It's intent is not to replace the advice of a veterinarian nor to assist
you in making a diagnosis of your pet. Please consult with your own veterinarian
for confirmation of any diagnosis. Your pets life may depend on it.
