A diagnostic approach to canine otitis externa

In this video interview with dvm360 ahead of his lectures at the 2026 Veterinary Meeting & Expo, Darin Dell, DVM, DACVD, shared additional insight into the diagnostic approach for canine otitis externa. Throughout the interview, he shares why topical treatments for the ears can be a better option, why veterinary dermatologists do not regularly perform ear cultures, and more.

Below is a partial transcript, edited lightly for clarity.

dvm360: How is an ear cytology performed, and what specific findings would indicate a need for a bacterial culture and sensitivity test?

Darin Dell, DVM, DACVD: The strange thing about this is that dermatologists don't actually do a lot of...ear cultures. It's not something we do very often, and that's because you can achieve 100 to 1000 times the antibiotic concentration when [you] treat topically. Most cultures are going to give you sensitivity based on a blood level of an antibiotic, which is great if we're dealing with a skin infection or a respiratory infection. But in the ear, we're going to treat topically, so we can get a lot higher concentration. Typically, I wouldn't do an ear culture unless we had otitis media. That's a definite time to do an ear culture, or if I [were] seeing a dog that had literally been on every antibiotic there was, like everything they've seen. So then I would do it just [to] narrow my choices.

That's one of those misnomers that we don't actually do a lot of them. It's...just something we don't do a lot of. We should be doing [the ear smear] every time. That's just trying to get a sample, usually with a Q-tip from the horizontal canal, rolling that onto a slide, a glass slide—however you prefer to do it—and then using Diff-Quik stain to look at it.

There, we're looking for [whether] you did see on that slide—a whole lot of cocci, a whole lot of rods, [or] a lot of neutrophils. [That may] also encourage you to do...that culture, or at least think differently about your treatment.