Cat with abscess

Question
I have an 8 y.o. cat who developed an abscess under his chin. The area is tender and he will not let me touch the area. He had the swelling for a day or so when I noticed it. The second day the abscess had ruptured and drained. He seems to be feeling better and is eating, however he still won't let me touch the area. I have an unopened bottle of Gentamicin Sulfate Ophthalmic solution. After doing some research online I found it is safe (having taken not of the listed side effects) for use with cats. My question is can the Gentamicin mg/ml be given orally? If not can it be used topically (i.e. into the opening of the abscess). This is the second day since it has drained. Thank you for taking the time to read/answer my questions.
Sincerely, Eric Bonfietti

Answer
Gentamycin is not absorbed when given orally, so don't give it.  You can use the solution in the wound topically.  Once the abscess ruptures, all of the toxins can drain out of the body and the cat will feel better.  Flush the cavity with warm water a least once a day and it will heal up over a week or so.