General Antiseptic for senior dogs?

I think you mean anesthetic, not an antiseptic. It is true that older, weaker dogs run a greater risk of actually not being able to wake up after being put under but from personal experience, take your dog in to get assessed by a vet. My parents' Cockapoo, who was 11 or 12 at the time of her dental surgery (they removed 4 or 5 infected teeth) had no problems at all. Granted she was not in the best shape of her life at the time of the surgery (but still very spry for an 11 year old dog), she still pulled through fine.

I'd let the Vet or the Specialist make that call. I know that if it's too big of a risk, they will refuse. Hope that helps.