I guess I wonder what kind of vet school graduate would want to work in what is essentially a chain store. The only answer I can come up with is; the ones that can’t get a job elsewhere.
The thing about giving you more wormers, I totally understand. Testing negative for heartworms doesn’t have anything to do with intestinal worms, which is what they gave you wormer for. A lot of vets will give wormer preventively for very young pups, because it doesn’t take very many worms to become a big problem for such a small animal. The wormers in the Quadriguard may be dosed to prevent reinfection, but not dosed to wipe out an active infection and they may need to be repeated at a different interval than once monthly.
$400 for a neuter is a bit much to pay for convinience, which is what you are paying extra for on everything else.
