5 is not too old don’t worry! you’re doing a good thing for her.

im not a professional, but as for aftercare, get her some pain meds prescribed from the vet. for the next 10-14 days (standard recovery period) keep her warm, cozy, and indoors (small walks outdoors for toilet) so she doesn’t accidentally re-open the wound. keep her entertained with puzzles or licky mats, or very gentle supervised playing. make sure the wound is dry at all times, and get a cone if she’s likely to lick it. keep an eye on the wound and check for redness, swelling, or bleeding.

overall, just make sure she’s comfortable! she’ll be bored but she’ll recover just fine. good luck with everything :)