first let me say he has an appt with vet on thursday...i just got this lil guy 2 days ago and i am wondering if its possible he has worms or if this is normal? My basset looks rather skinny during reg day unless he has jut eaten or drank a lot of water then his tummy is huge. i am thinking worms! i will find out next week. if it is worms would the heartworm preventative i just gave get rid of it? it was tri heart my vet sold me 1 dose since he couldnt do the full exam yet and the dog has been on the preventative non stop. but the tri heart is for intestinal and heart worms would this get rid of a worm problem as well or prevent future problems??? also he is on a holistic puppy food!...also no visable worms in stool?

EDIT: 3 month old basset hound.....my number lock is not on!!!