Ear infections in cats: signs, treatment, and prevention

What causes ear infections in cats?

The most common cause of external ear infections, called otitis external, in cats is infection by the ear mite Otodectes cynotis. This mite alone accounts for around 50% of ear infections in cats.1-3  Environmental and food allergies are the next most common cause. Cats also have a higher incidence of polyps and overgrowth of cerumen glands (ceruminous cystomatosis).1,4  Foreign bodies are also another common cause. Other, less common causes, should be evaluated for by your veterinarian.

Factors that increase the risk of developing otitis can be internal or external. Internal factors include increased soft tissue in the ear canal, stenosis (narrowing) of the ear canal, and excessive hair in the canal. External factors include increased humidity and temperature of the environment, swimming, and bathing. These factors increase moisture in the ear canal which favors overgrowth of yeast and bacteria.1

What are the signs of an ear infection in a cat?

The most common clinical signs are scratching at the ear(s), head shaking, red/irritated ear pinna(s), or foul odor from the ear(s), and pain from the ear(s).

How do veterinarians check cat ears?

The first part of the ear exam includes your veterinarian looking into the ear canal with an otoscope. This will help look at the tympanic membrane (ear drum) for possible rupture. This is an important step as some medications should not be used if the tympanic membrane is not intact. This will also help look for foreign bodies and changes to the external ear canal.

The second part of the ear exam includes the cytology of debris from the ear. This is a microscopic evaluation to look for an abnormal amount of bacteria or yeast, parasites, or evidence of inflammatory cells. This exam is important as it helps determine which medication would be most useful for treatment. Rods are a type of bacterium found in ear infections that often require stronger antibiotics and a specialized ear cleaner. This is due to rods having a cell wall that needs to get broken down for medication to penetrate the bacterium and kill it.

If ear infections have been a chronic issue, your vet may recommend culturing the debris. This can help determine which medications will be the most effective.

How are ear infections in cats treated?

Finding the underlying cause for targeted therapy is recommended. This is especially important for ear mites.

Ear Cleaning- Removing debris from the ear canal is an important step for treatment as the debris can deactivate some topical treatments and prevent the medication from contacting the canal. Your veterinarian will recommend a cleaner that will be best to help treat. These products often have a drying agent to help reduce moisture in the ear canal.

Topical Therapy –  Steroids, antibiotics, and antifungals are indicated based on the infection type. These products are often found all together in combination products. Your veterinarian may apply a product that stays in the ear for a few weeks or have you apply the product once or twice daily for 2-4 weeks.

Cats tend to be more prone to deafness (ototoxicity) from topical treatments than dogs.

What happens if a cat ear infection goes untreated?

Ear infections can spread from the external canal to the middle (otitis media). This condition can cause signs such as a head tilt, ataxia (off-balance walking), decreased eating, and pain in opening the mouth. This condition usually needs systemic medications and may even need a sedated cleaning and sampling of the middle ear, called a myringotomy. Some veterinarians may also recommend advanced imaging including a CT scan or MRI to check for abnormalities of the middle ear.

Ear infections may also lead to aural hematomas. This is a pocket of blood that develops on the ear pinna and is caused by the breaking of the small blood vessels of the ear. This condition can be fixed surgically or nonsurgically.

Cats may also develop a condition called proliferative and necrotizing otitis externa. This is a rare disorder with an unknown cause.5,6 This condition is typically treated with topical steroids.5

Monitoring

Frequent follow-ups are important for otitis with repeated cytology to make sure that the treatment doesn’t need to be modified. It is also important to monitor for deafness. This can be caused by cleaning the ears or certain antibiotic usage. 

One of the most effective ways to prevent infections and other health issues is by conducting comprehensive health checks for your cat to identify any unusual signs promptly.