Otodectes Cynotis, this mite has been proven to be found in
dogs, ferrets, foxes, and of course, cats. It is found all around the world,
America, Europe, Asia, Middle East and Australia.
The mites live in the ear canal of the cat. Most times there
can be over a thousand mites present in the ear without any apparent mites
appearing on the surface of the feline host.
Now we must remember the life cycle of these mites. First of
all, the female mite secretes a fluid that helps her eggs to be glued onto the
cat's ear canal. The eggs typically require 4 days of incubation prior to
hatching. The life cycle includes a larva, a protonymph, and a deutonymph. Each
stage takes a minimum of 3 to 5 days to develop, and the development is
followed by a quiescent period of about 24 hours during which time the mites
molt and shed their cuticles. As soon as the adult emerges from duetonymph
cuticle, it will seek out and form a pair with a deutonymph. The complete egg
to egg cycle took aproximately 18 to 28 days (about 3 weeks).
Transmission between hosts is by direct contact. The mites
seem to require a relatively high humidity for survival and seem to rapidly
dessicate at typical room humidities.
As for the clinical signs and pathogenesis, most cats tend to scratch a lot, however, some cats vary in
their abilities to serve as hosts for Otodectes cynotis. If we observe close
enough we can see that most cats can have severe lesions with significant
quantities of dark cerumen and sometimes even blood present in their ears but
one or two mites, other cats will have very clean ear canals, almost devoid of
cerumen and detritus but have lots of mites. Still other cats can host huge
numbers of mites in their ears and still have shown very little in the way of
outward signs of infection. Ears of cats with very large numbers of mites tend
to contain a dry waxy parchment-like material that occurs as sheets throughout
the ear canal. These layers of sheets will contain mites throughout and consist
in part of rafts of eggs that are embedded in the material. These ears tend to
not contain large quantities of wax.
The Identification is relatively simple, no other
non-burrowing mites of large size are typically found in the ears of the cat. The
living mites appear as small white organisms that can be seen moving about
within the ears or on swabs of deteritus removed from the ears. An examination
of the distal portions, pretarsi, of the anterior pairs of legs will reveal the
'wine glass' shaped caruncle on a short pedicel. The eggs are white, oval, slightly flattened
on one side, and are 166 to 206 µm long.
As Veterinarians we have now days multiple options regarding treatment for otodectes cynotis, and of course as we know, not all patients can react properly to a certain treatment, and that is why, it is our job to test and provide the best treatment for each patient.
Our best chance on treatment can be Pyrethrin, there are
several presentations containing different type of compounds, such as Otomite
Allerder by Virbac, Nolvamite by FortDodge, Eradimite by Solvay, Aurimite by
Schering Plough. Also we can use Rotenone containing compounds such as Er
Miticeby Phoenix, Ear Mite Lotion by Durvet, Ear Miticide by Vedco.
If we want to go beyond, because our patient has a greater
infection we can also use Otomax, which is a mineral-oil based otic ointment
containing gentamicin sultate, betamethasone valerate, and clotrimazile.
However, if our patient is not too infected, or if the
patient has shown in previous ocasions to be picky on the meds, we can also do
a test using natural products such as 2ml of mineral oil based and 30 seconds
of external massage of the base of the ear of the cat, and we can see if after
2 treatments one week apart we are able to see a difference. Of course if we
decide to go all natural with the mineral oil, we might notice that this oil
might tend to leak from the ear, and the hair on the head of the cat might
appear oiled for the first day or so after treatment.
And of course as we all know, when it's about a fiery cat we
can always go with shots, Ivermectin injectable, even if is not officially
approved in cats, ivermectin has been used to treat feline infestations with
otodectes cynotis. The most typical dosages are 0.2 to 0.225 mg/kg injected on
one occasion or on two occasions with a 3 week interval between injections.
As Veterinarians we most be aware of the toxicity of
Ivermectin when used not just in cats but in dogs too, 0.5mg / kg body might
just be the limit of this medication, any more than this and it can become
extremely toxic. However, Ivermectin can be used safely into the ear canals in
drop presentation, it really is highly effective!
Also, we most remember, that one dosage of medication, which
ever we choose for our patient may not be enough, and we most tell the owner
that they need to return within 2-3 weeks for a follow up visit, and then we
most check our patient again and see if there's been improvement.
Now let's talk about the hazzard towards humans, there is a
slightly chance for this mite to be transferred to humans, since 1978, there
haven't been any reports, so in few words, it can be hazzard towards humans,
however is very rare.
It is very important to remind the owner of our patient,
that if they have any other pets at home, they should treat all of them, since
ear mites can be easily transmitted among them, even if it's a dog or a rabbit,
or a ferret, even a parrot.
We hope that this post is of some sort of help for you, or
as a kind reminder since ear mites are very common among cats and dogs.
Cheers!
MVZ Carolina Pruneda
Cheers!
MVZ Carolina Pruneda
