Killing a dog with a treatable condition such as heartworms is inhumane. It is not necessary, heartworms are very treatable. Give all the dogs that enter this county run shelter a chance to be adopted or released to rescue, regardless of heartworm status.
This is teenie, a dog abandoned and hwp at 7 months old. She was treated with fast kill at the Orlando med center for $300. A small price for a life.