My vet said that he only ever really sees guinea pigs when something is wrong with them. (and he's one of the best for small animals in the UK) He advised me to start doing yearly health checks and when they get to senior years do every half year. If more vets see Guinea pigs for just health check overs, like cats and dogs, can't be a bad thing really.
I would like to do this because I can't check all teeth myself, I can't feel for lumps and bumps or any abnormalities like a vet can, can't check temp, hydration.. Things like this