Dissolving is good, but if the vet told you to take them out, like Sweetie said, they're not dissolving. The typical thing to use these days is tissue glue, which is a lot like super glue and it dissolves over time. The dissolving stitches are usually used internally these days, but can be used externally as well, if the vet doesn't have tissue glue. Using typical stitches is a bit old school, and makes me worry about how up to date your vet is. Don't worry about it now, just let Donut recover, but it might be a sign that in the future you need a different vet.
I had dissolving stitches for my wisdom teeth--they just fall out over time as the wound heals--a lot easier than having them removed.
Did you get take-home pain meds? Did he eat or poop overnight?
It's good that he was drinking. If he hasn't eaten, listen to his belly for gurgles--if he has them, he probably has gas from the surgery--they intubate them sometimes during the surgery (put a tube down their throat) which can introduce gas into the GI tract. Also, not eating can lead to gas, which is painful and leads to more not eating. Gas can be treated with a few doses of simethicone (Ovol, Mylicon brand names) made for babies. We had to do this for our nethie when ge got neutered.
