Causes and treatment of ear infections in pets

By Andrine Belliveau DVM

In the spring and summer, one of the most common questions veterinarians are asked is “Why did my pet get an ear infection again?” Unfortunately, recurrent ear infections are one of the most common health issues in dogs. The ear is made up of 3 parts – the outer, middle, and inner ear. Usually an ear infection refers to an infection of the outer canal. Occasionally, a severe outer ear infection can rupture the eardrum and cause a middle ear infection.  All ears have low levels of yeast and bacteria in them normally – they are organisms that help “clean up” any debris that makes its way into the ear.

When the bacterial or yeast population suddenly increases, an infection is the result.

We can see recurrent ear infections for a number of reasons. Dogs that like to swim tend to collect a lot of water in their ears. If this is not cleaned/dried out regularly, it provides a perfect environment for organisms to grow. Dogs with hair in their ears (e.g. poodles) tend to collect too much debris. The hair does not allow debris to escape easily, providing too much food for the organisms in the ear and resulting in an infection. An easy prevention for this type of infection is to have your dog’s ears “plucked” when they are groomed to remove the excess hair.

The most common cause of recurrent ear infections is allergies. Studies have shown that approximately 25% of dog with allergies show only recurrent ear infections as a sign. Dogs and cats can have food allergies, or environmental allergies such as dust mites and pollen. If allergies are suspected as an underlying cause to your pet’s ear infection, we may talk to you about allergy testing, diet trials (to see if we have an allergy to a particular ingredient), or medication to manage the allergies long term.

In cats, a very common cause of ear infections is the ear mite.  Although many dog owners suspect mites, this is actually a relatively uncommon cause of infection in dogs. The key to treatment for ear mites to treat all affected pets in the house at once – otherwise it will continue to cycle through the household.

An ear infection can be diagnosed with a physical examination at the vet. We often will perform cytology with ear swabs to see if the cause is mostly bacterial, mostly yeast, or both, so we are able to select the right type of medication to treat the infection.

Although ear infections cannot always be prevented, the frequency of infections in problem pets (dogs that swim, or pets with allergies) can often be decreased by cleaning the ears frequently.  There are a number of ear cleaners for specific issues – such as yeast overgrowth. To treat an infection, pets will be sent home with once or twice daily topical medications or receive an in-hospital “pack” treatment for a dog that is difficult to medicate at home.