Heart worm medicine doesn't prevent infestation, it just kills them in early stage before developing fully into adults. The dead larvae are small enough to pass through the pulmonary system without causing serious problems. A dog with full infestation of adult worms is at risk for the drug because once they develop into adult size, killing them will cause dead worms to pass through the pulmonary system like huge clots. I've heard of vitamin C therapy for snake bites. My vet recommends 2-3 Benadryl tablets per 20 lbs. dog weight to prevent swelling which can close the windpipe. Take off all collars as well. Not sure who brought up the vitamin C or heartworm issue, but I recall a bright flash of light and disorientation when I peeked. Smelled sulfur, too.
Gil
