But what was his reasoning behind it? Where's the infection? Did he do a fecal to clarify he needs a dewormer? Is there weight loss to even suspect parasites?
A vet is a vet. 99% of vets their goal is to get some money out of you. If you're lucky to find the 1% that says "It's not necessary, this route is cheaper." Then don't change vets. Even I have to question my vet sometimes on his motives. I'll take a gravid female in for an eye infection, he'll ask when she last ate, I'll say two weeks or so, he'll jump right into antibiotics and this liquid calorie food to give her even though she's not eating due to being gravid and not losing weight. You really have to educate yourself before going in.