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Otodectes cynotis,
the common ear mite, is a major cause of external ear disease in cats.
These mites are highly contagious and feed on superficial epidermal
debris and waxes in the ear canal. Clinical signs include intense
itching, dark black discharge (like coffee grounds) in the ears, and
shaking of the head. In severe cases the infection can extend through
the eardrum. Other complications include trauma to the head and ears
from scratching and aural hematomas from head shaking.
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Life Cycle
The life cycle of
ear mites is 3 weeks. The egg is laid with a cement that sticks it to
the substrate (skin). After a 4-day incubation period, it hatches to
produce the six-legged larva. At this point, the larva feeds actively
for 3 to 10 days, then hatches to the protonymph and eventually to an
adult mite over the next 6-10 days. The adult can live off the host
from several days to 2 months.1
Transmission
Ear mites are
highly contagious and especially prevalent in young animals. They are
most common in kittens. Many species of carnivores can become
infested, as the mites are not host specific, meaning that they can be
spread from dogs to cats and vice versa.
Diagnosis
The diagnosis is
based on clinical signs and finding the mites on otoscopic
examination.
Treatment
Treatment of cats
with ear mites is easy and efficacious. Revolution (selamectin) is
currently our product of choice for treatment of ear mite infections
because it kills mites both in the ear canal and on the skin. This is
a topical solution that is applied to the skin of the infected animal
and to all the other exposed animals in the household. A single dose
is applied on the skin of the cat’s neck. The cat is re-examined in
one month to assure the condition has resolved. In a few cases ear
drops may be used to treat ear mites. If this form of therapy is
selected it is very important to follow the directions and treat for
four weeks.
Ear mites are very painful and should be treated promptly and
appropriately so that our cats can live comfortable and happy lives.
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1
Ackerman,
Lowell, Practical Feline Dermatology, American Veterinary
Publications, Inc. 1989.
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