Expert: Dr. Louis N. Gotthelf - 1/13/2011

Question
QUESTION: My 13y/o dog was treated with Neomycin,Polymyxin B Sulfate Dexamethasone Ophthalmic Suspension for an "Yeast Ear Infection" after 3-4 days he was deaf. This occurred Nov 12, 2010. Do you think his hearing could return? Is there a way to figure out if the hearing is totally gone? We have tried the smoke alarm buzzer which is loud and piercing, it's hard to say sometimes he seems to turn his head toward the sound. I live in the Chicago area, if you can make any suggestions

ANSWER: Both polymyxin and neomycin can be toxic.  I can't imagine a vet prescribing that for a yeast infection.  Whether the hearing will return will depend on if the eardrum was ruptured and how much permanent damage was done by the drugs. The only thing you can do is to wait it out to see if any of the hearing returns.

---------- FOLLOW-UP ----------

QUESTION: Our dog was re-examined today and is definitely deaf.
Also found to have a ruptured right eardrum
left is intact. Now on oral cephalexin to treat infection in right.
Got an injection of steroid also today. Mometamax is the ear drops he received not Polymxin. We are very sad about all of this.

Answer
Oral cephalexin will not do much in a middle ear infection. You said that your dog had a yeast infection.  Cephalexin does not kill yeast at all. These middle ear infections are best treated by flushing the middle ear out, drying it, and infusing a nontoxic antibiotic into the bulla.  The gentamycin in the Mometamax getting through the ruptured eardrum is probably what caused the ototoxicity.