Ototoxicity with a ruptured eardrum: what to use for ear flushing
8-year-old domestic shorthair cat with chronic right otitis externa. Under anaesthesia, video-otoscopy shows that the tympanic membrane is ruptured and there is exudate in the middle ear. You are going to flush the canal and middle ear.
Which solution is the safest for flushing?
chevron_right Show answer and explanation
A. Diluted chlorhexidine, because of its good antiseptic effect
Chlorhexidine is ototoxic in contact with the middle and inner ear, and cats are particularly sensitive. It can cause deafness and vestibular syndrome; avoid it if the eardrum is ruptured or cannot be seen.
B. A commercial ceruminolytic cleaner containing alcohol and salicylic acid
Many ceruminolytic and alcohol-containing cleaners are irritant and not designed for the middle ear. With a ruptured eardrum, use only products of known middle ear safety.
C. Warm sterile saline
Correct. Warm sterile saline is the safest option for flushing the middle ear (Tris-EDTA is also considered safe). Even so, in cats flushing can cause transient Horner's syndrome or vestibular signs due to manipulation of the middle ear, so warn the owner.
D. A gentamicin solution, to treat the infection while flushing
Aminoglycosides (gentamicin, neomycin, amikacin) are the classic example of ototoxic drugs. Placing them in the middle ear risks deafness and vestibular damage.
lightbulb Key takeaway
Before putting anything in an ear, check that the eardrum is intact. If it is ruptured or cannot be seen, avoid chlorhexidine, aminoglycosides and irritant cleaners. Signs of ototoxicity: head tilt, ataxia, nystagmus and deafness; in cats, Horner's syndrome as well.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.