Benzopencillin (antibiotic) for dental

I have a dilemma. So my cat is going in for dental tomorrow and I have reservations with Convenia so the vet suggested Benzopencillin which is a one time shot, but the vet said it doesn't last long like Convenia. He said I should avoid any oral antibiotics since my cat has megacolon and it could disrupt the movement of her colon so to speak.

I'm not quite sure what to do. Any suggestions? Has anyone used Benzopencillin for their cats?

Good for you for avoiding Convenia, especially with a cat who could have colon issues.  It stays in the system 63 days and any cat given Convenia should be on probiotics for the entire 63 days.  Most vets don't seem to know this or tell their clients about this, but a few do.  I have found the long-acting penicillin to be well tolerated in general, and again suggest it is a good idea to give probiotics to any cat receiving antibiotics.

So your cat has had penicillin for dentals before?