We just got Wrigley from a rescue last weekend. Last night we took the three b's out on a hike and after Wrigley went poo we noticed that he had several worms in it. YUCK!:eek: Anyway, one of my friends told me a vet once told him not to buy over the counter worm meds unless you have tested for heartworms first (we are trying to avoid another vet visit – we were just in there last Monday getting Wrigley checked out). Anyway, he said that the vet told him that if you give worm meds to a dog and he happens to have heart worms the meds can kill him. Does anyone have any info on this topic?