Yes, you can. It's important to remove all food for two hours before the PS test. What was his vet appointment about?
Well it wasn't really an appointment, just a walk-in visit to get his nails trimmed. We also wanted to talk to his vet about some things, but she was in surgery at the time, so we're hoping she'll call us back later today.
Yes, the Hill's Diet W/D dry food is what he has been eating since he was diagnosed. We still plan on transitioning him to wet food, we've just been trying to figure out how to go about getting the wet food, which I know sounds ridiculous, but with our financial situation we always get all our necessities (groceries, etc.) at the beginning of every month because we usually don't have any money left to buy things throughout the month as needed, so if we were to be giving him 2.5 cans a day, as suggested here, that would be around 75 cans a month (depending of course on how many days are in the month), so we're just trying to figure out the best way to go about it with the least amount of hassle.
Yes, Fancy Feast is the one we've been leaning towards, but thank you for the extra suggestions, we'll look into those and see if any of them will work out better price-wise.