Ear infections in dogs and cats

Ear infections can be one of the most frustrating conditions to treat! If your senior pet has never had an ear infection, they probably never will. Other pets, particularly dogs, have a constant, lifelong battle with ear infections. Some dogs it’s just one ear, but always that same ear! What gives?

These dogs that seem to be constantly battling ear infections often have a condition that predisposes them to the infection. Until the predisposing condition is addressed, the recurrent infections will persist. The most common predisposing conditions are seasonal allergies (atopy), food allergy, or anatomical abnormality. Determining which of these is wreaking havoc in your pet can be very difficult and time-consuming, but is possible!

Diagnosing the underlying factor can depend on where you live, as different parts of the country have different allergens dogs can be exposed to. Anatomical abnormalities are more straightforward to diagnose (ie – the ear canal on a cocker spaniel). Food allergies are another difficult-to-diagnose predisposing factor. (Here’s my article on food allergy and how to diagnose it).

In terms of the actual ear infection, they usually come in three basic types: bacteria, yeast, or both. We need to know what is living in the ear so we know which medication will kill it.  We can look in the ear canal, but we can’t tell just by looking at the debris what is living in it.

Few things are more frustrating than an owner telling us his dog is pawing and rubbing his ear for a few days, but they cleaned it out really well for the appointment. They usually use something that has no business being in an ear, like peroxide or alcohol, to boot! I tell my clients not to tamper with evidence. If you suspect an infection, you’re probably right. I need to see it au natural. Step away from the peroxide and call your vet! Why do we want to see the ear goo? Cytology!


“Ear cytology” means microscopically evaluating the cells in the ear debris. We’ll smear a sample of the ear goo on a microscope slide. Then we treat the slide with three stains to make the micro-organisms show up better. Finally, we read the slide under the microscope. All this takes about 10 minutes, so your vet will have an answer right away. Based on what we see, we’ll prescribe the appropriate medication and/or cleaner to target the infecting agent.

In some cases, a dog that has had infections off and on for years can develop a bacteria that is resistant to the usual medications. This bacteria is usually what we call a “rod shape” although these days some round bacteria are getting in on the resistance game. In this case, your vet might want to take a sample of the ear debris and send it to the lab for a “culture and sensitivity”. The lab will grow the organisms in a petri dish, then test them for which medication will kill them. We use that information to prescribe the best treatment.

There are a variety of ear medications out there these days. Sometimes you’ll get a cleaner from your vet to flush all the junk out. In pets with a history of chronic ear infections, we’ll sometimes have you use the cleaner even when there’s no infection, to try to keep the infection at bay. There may be an ear drop you apply once or twice a day. Some newer medications have come out that we simply instill into the ear one time, and they treat for a month! The treatment your vet chooses depends a lot on what they see under the microscope.

Who knew looking at some smelly ear goo could be so helpful?