The very minimum should be once a year for bloodwork. An office visit averages around $40 here, and bloodwork about $110. For an entire year, that is not a lot if you put money into a savings monthly just for vetting. What would you do if there was an emergency or accident? I also have Care Credit just in case anything happens. I applied for it when I had ok credit, and they gave me a $3500 limit. when my credit went bad, all my other cards canceled me, but CC didn't, thank god. I keep it just in case, and for peace of mind.
That said, Uni goes at least a few times a year for heartworm rx fill up, nail trims, yearly exam bloodwork, and the occasional thing that pops up.
Now that I think of it, when was the last time I went to the dentist?!