A diagnostic approach to canine otitis externa

During this video interview with dvm360 ahead of his lectures at the 2026 Veterinary Meeting & Expo, Darin Dell, DVM, DACVD, shared more insight about the diagnostic approach that can be used when presented with 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: So 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. So 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. So 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 was 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] kind of narrow my choices.

That's kind of 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; the ear smear we should be doing every time. So 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.

So there we're obviously looking for, you know, if you did see on that slide a whole lot of cocci, or a whole lot of rods, a lot of neutrophils; [that] would also maybe encourage you to do...that culture, or at least think differently about your treatment.