Causes of otitis externa

In this interview, Jason B. Pieper, DVM, MS, DACVD, assistant professor at Iowa State University talks about various causes of otitis externa, including the top cause. In the video, he also cautions veterinarians against believing that atopic dermatitis cannot cause unilateral otitis, explaining that it can happen.

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Below is a partial transcript, which has been lightly edited for clarity:

Jason B. Pieper, DVM, MS, DACVD: The causes for otitis externa. I mean, definitely the number one is going to be allergies, which then usually are going to be food allergies and atopic dermatitis or environmental allergies. So those are by far the most common causes of them.

Again, it can help whether it's seasonality to differentiate what the underlying cause is and kind of working those up. But that's definitely the number one cause for otitis externa.

Otherwise, you're going to get a lot of the similar causes for pyoderma, you know, similar to otitis, of you know, is there endocrinopathy going on? Is it hypothyroid, Cushing’s, because of the immune suppression do we get recurring otitis because of that, you know? Is there a mass, you know? Is it a young cat as a polyp, or an older cat or older dog that has a mass in the ear, a tumor that needs to be dealt with?

You know, obviously, for masses, it usually helps if it's unilateral, that can kind of push you more that way. But don't fall [for] the mistake that atopic dermatitis can't cause unilateral otitis. I have seen it. It's weird, but I have seen it, so it does happen. And then you still have your other ones of like autoimmune diseases that can be going on. Foreign bodies, depending [on] if their dogs are hunting dogs, we definitely see foreign bodies, you know…