Ear Mites In Cats

If a cat is suffering from otitis, it’s likely caused by ear mites. The good news is that this condition is easy to treat!

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Cats are often less tolerant than dogs of topical ear medications. Burkhardt-Mayer-Fotografie GbR/iStock/Thinkstock
Dr. Brian Roberts

Hello cat lovers! For as long as I can remember, I’ve had cats. We adopted our first cat from the local shelter when I was in first grade. Her name was Suzy, and she was a bit of a mess when we first took her home. While the shelter did the best it could back in 1977, she came to us thin, with a matted coat and very irritated ears.

I definitely remember going with my mother to the veterinary office. This was the first time I had been to one. The waiting room had the traditional 1970s wood paneling and it was packed. It looked like a bus terminal for Noah’s Ark! There were dogs and cats waiting with their owners, a person with a giant cockatoo and an exotic dancer with what I could only assume was a boa constrictor in a pillowcase. The vet, a kind, older gentleman, immediately knew why Suzy’s ears were bothering her.

“She’s got ear mites,” he declared.

The look on my mother’s face was priceless. Her immediate concerns were: (1) could we catch them and (2) should Suzy be taken back to the shelter.

Luckily, the vet quelled her fears and we were able to get the infection treated, but back then it wasn’t as easy as it is today. Suzy needed eardrops, which she really disliked. It was only after some lectures in dermatology during my veterinary training did I learn that cats tend not to tolerate topical ear medication like dogs do. Cats can develop reactions to the medication, causing the irritation of their ears to worsen.

Ear Mite Identification, Life Cycle And Transmission
Ear mites are known by their scientific name Otodectes cynotis. Ear mites are arthropods, having an external skeleton made of keratin. To the naked eye, they are about the size of large grains of white sand. Microscopically, they have six legs and look like ticks. The mites live in the external ear canal and cause irritation because their saliva leads to an allergic-like response by the host. It’s similar to the raised, red lesion you get from a mosquito bite. It’s the mosquito’s saliva that causes the immune system to react, causing the inflammation.

The mites feed on debris such as wax and dead skin cells. They may also feed on live skin cells lining the ear canal, as well as bodily fluids. Ear mites lay eggs three to four days after mating. The eggs hatch into larvae after a few days. Larvae turn into pupae, and then there are two nymph stages. The entire life cycle from egg to adult takes about three weeks.

It is believed that mites spread from one host cat to another by direct contact. One study found that mites not only live in the ears of cats, but also on their flanks. That’s likely why many cats in shelters will have them. Temperature and humidity are factors that are important for the ear mites to reproduce and thrive. The higher the humidity (80 percent or higher is required), the better for the mites.

Symptoms Of Ear Mites In Cats
Otitis (ear inflammation) results in painful, reddened, swollen ear canals that typically have a fair amount of dark, waxy exudate called cerumen. Bacterial infections, yeast infections, growths such as ear polyps and ear mites all cause similar inflammatory changes.

Approximately 37 to 50 percent of cats with otitis have ear mites. Common findings of infected cats are: (1) large amount of dark-brown exudate and (2) abrasions, cuts and scabs from scratching the outer ear (pinna) and the skin of the ear base. These wounds are self-inflicted, caused by cats scratching and rubbing their own ears. Therefore, most cats with ear mites will be scratching their ears, rubbing them with their paws and shaking their heads. It is interesting to note that approximately one out of every 10 cats with ear mites will have no symptoms!

Diagnosis Of Ear Mites
Direct visualization of the ear mites is how they are diagnosed. Sometimes, just using an otoscope will allow the veterinarian to see the tiny mites crawling around inside the ear canal. Because of the large amount of detritus and earwax, the mites can be difficult to see during the exam. Plus, imagine how you would feel having a very painful, red, itchy ear. Now imagine someone sticking an ear cone inside of it. I bet you would jump out of your chair! The more inflamed and painful a cat’s ears are, the less tolerant she will be to examination. Sometimes a sedative and pain medication are recommended to be used so a more thorough evaluation can be performed.

The “gold standard” for ear mite definitive diagnosis is to identify the mites microscopically. Your veterinarian will collect a sample of the ear discharge, mount it onto a glass slide with some mineral oil and look for the ear mites under a microscope.

Treating Ear Mites In Cats
There are many options of treatment for this parasite. Topical treatments like drops and ointments can be used, but only after the ear debris has been cleaned out. Mild insecticides are the primary ingredients of topical drugs, including rotenone-containing compounds and pyrethrin-based products. Your veterinarian may prescribe an antibiotic, anti-fungal and anti-inflammatory ointment.

As I mentioned in my story about Suzy, topical medications can be irritating to cats and can be very challenging to administer. I bet it won’t take but just a couple of treatments before your cat hides somewhere — usually under the middle of your largest bed — when she thinks it’s ear drop time! Luckily, there are other treatments that do not involve daily drops of medication into the ears.

The topical flea, tick and heartworm preventative, selamectin, was found to be effective, killing the ear mites 10 to 12 hours after administration. A similar drug, ivermectin, has been used for quite some time. It is a subcutaneous (just under the skin) injection given once and then repeated three weeks later. Ivermectin, if overdosed or if used in kittens, can cause side effects that result in tremors and other neurologic problems, even death. So, don’t purchase this product from your local feed store and use it yourself! It should only be administered by your veterinarian or their staff after a proper dose has been calculated and double-checked.

So, recall when I mentioned that my mother was concerned about us catching ear mites from Suzy. Well, it’s possible, but highly unlikely. I could only find two reports of persons infected with Otodectes cynotis and it’s unclear if they truly caught the infection from animals. Both reports are more than 35 years old. However, other cats, dogs and ferrets could become infected from a cat with ear mites.

Remember This
Some key points about ear mites in cats:

  • Ear mites are a common cause of ear infections; up to half of cats with otitis have ear mites.
  • Ear mites are spread by direct contact, common in areas with numerous cats.
  • Common signs of ear mites are a dark, waxy and dry discharge, along with pain, scratching and abrasions to the outer ear.
  • Direct, microscopic identification confirms an ear mite infestation.
  • Topical medications applied to the ears or skin and injections can control ear mites.

My hope is that you never have a problem with your cat’s ears. If your cat does get otitis, then it’s likely due to ear mites, which are pretty easy to diagnose and treat.

Article Categories:
Cats · Health and Care


  • So, Puglet, I know you didn’t mean to scare the poop out of us, but we love you all so much, we can’t help but be worried. Silly Puglet…don’t you know how much you, and Thumbs, and Dutch mean to those of us who love you? So I am hugigng every pug and person in sight for you.

    Francisco August 26, 2015 1:51 am Reply

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