Chronic otitis externa: Why the ear isn't clearing, and how to fix it

Chronic otitis externa is among the most frustrating conditions in small animal practice, leaving patients uncomfortable, owners exasperated, and veterinarians frustrated. Julia Miller, DVM, DACVD, a veterinary dermatologist with Animal Dermatology Clinic in Louisville, Kentucky, told attendees at the Fetch dvm360 Conference in Kansas City Missouri, that biofilm and unmanaged inflammation, not antibiotic resistance, account for most of the ears that never clear. Her session laid out a sequence practitioners can run in general practice, beginning before any medication is dispensed.

Set expectations, then run cytology every time

Severe ear cases are not one-visit cases, and clients need to hear that at the first appointment. Miller tells owners, "It matters tremendously to me that you come back for rechecks." She warns them that resolution may take a month or more, that long-term preventive care is likely, and that chronic ears are not cheap to treat.

Cytology comes next, without exception because it identifies rods, which shift her prognosis, flags biofilm, and shows whether the organisms have changed at recheck. This is also when the medication should change too. Miller also urged sampling the pinna separately. She shared that in a case of hers, a tape impression of the pinna showed yeast while the canal grew rods, and the patient needed both a topical and an oral antifungal. She also told attendees that they can utilize their technicians by having them collect and interpret ear cytology’s as part of the visit.

Look in the ear, but don't fixate on the eardrum

Miller asks for an otoscopic exam on nearly every ear, with exceptions. A canal that is red hot or badly ulcerated, in a patient fighting the otoscope, can wait. She said she does not consider a deferred exam a failure on day 1. Unilateral cases are the ones that must be examined, especially in cats, where polyps and tumors occur in young and old patients alike. If the cat will not allow it, she told the room she will sedate the patient.

The eardrum is not what she is looking for. Otic medications are either ototoxic or they are not, she said, and a ruptured tympanic membrane does not change her plan, short of tympanometry.

"You cannot be certain that a dog has an intact eardrum ever," she reminded attendees.

What she wants is to rule out a mass or foreign body, and to spot the white plaques on the canal wall that signal biofilm.

Cleaning is what makes the drug work

"Not a single ear leaves my clinic without me or my technicians cleaning it," Miller said about ears with discharge. The reason is pharmacologic because organic debris inactivates almost every single ear medication we have. A canal full of pus will defeat any product placed into it.

Her in-hospital protocol is a cerumenolytic cleaner, a saline flush, and gentle suction at the canal entrance rather than deep in the ear. Painful ears are flushed under general anesthesia with a protected airway, since fluid can reach the nasopharynx in patients with middle ear disease. At-home cleaning helps in exudative ears, but only if the owner is shown how, and Miller has clients demonstrate their technique at recheck. "Please never send a cleaner out the door without instructions," she said.

Once a day, and more of it

Miller does not prescribe twice-daily otic medication. She said, "In ears, my number one goal is compliance." A product applied to the pinna instead of the canal cannot work, however good it is. She increases volume rather than frequency and fills the canal instead of counting drops. Compounded in-house preparations, typically a steroid, an injectable antibiotic or antifungal, and saline, allow that larger volume and let concentrations be tailored.

Biofilm is usually the reason

Millers describes biofilm to clients by having them imagine that the bacteria in the ear puts a little rain jacket on, and that rain jacket protects it from all of the antibiotics." Pseudomonas is the classic producer, but staphylococci and Malassezia can form it too. She suspects biofilm when discharge is thick and slimy regardless of color, when the canal is ulcerated, and when cytology shows wispy, veil-like background material. Enzymatic anti-biofilm products and N-acetylcysteine-containing cleaners are her tools.

Steroids, not NSAIDs

Systemic anti-inflammatory therapy is the other half. "Why are these ears painful? Because they're inflamed," Miller explained. “So do not use NSAIDs for these ears. Use steroids for these ears." She described a Pseudomonas case that resolved completely on a topical steroid and oral prednisone after the owner never started the prescribed anti-biofilm product, with no antibiotic at any point.

Her dosing runs higher than many practitioners use, and short courses do not need tapering. "The reason I taper pred is to limit side effects." Chronic hyperplastic canals, particularly in cocker spaniels, need weeks rather than days, and those patients she does taper. She switches to dexamethasone in dogs that have become steroid resistant and prefers it in cats. Oclacitinib does little for ear inflammation, she said, and "CytoPoint does literally nothing for ear inflammation."

Conclusion

Miller's takeaways came down to a short list: run cytology at every visit, clean the ear before expecting any medication to reach its target, treat biofilm as a target in its own right, and manage inflammation systemically rather than relying on the steroid in the tube. She was equally direct that none of it works every time, that dermatologists differ on the specifics, and that Pseudomonas cases still give her trouble. As she put it, "There is no one size fits all. Ears are all different."

Reference

1. Miller J. I hear you! How to manage frustrating, chronic otitis externa cases. Presented at: Fetch dvm360 Conference; August 28-30, 2026; Kansas City, MO.