Every practice management system can send a pet vaccination reminder. What it rarely does is cope with the answers: the owner who has moved, the cat that has died, the dog that is booked in already at the other branch, the reply asking whether the booster can wait until after a holiday. Those replies sit in an inbox, and the reminder that triggered them is counted as sent.
Good vet client communication is the follow-through. The reminder offers specific appointments, books the one the owner picks, updates the record when a pet has died or moved, and does it in a tone the practice has approved. A message about a pet that has died, sent again three months later, is the kind of mistake that loses a client, so record hygiene is part of the job.