My folks in FL just lost their 1Yr old black Lab. They also have 3 y/o ridgeback who is smarter than most people i know. She came across an eastern Diamondback on their property, and immediately ran whereas the puppy (samson) went over to investigate as all puppies with no sense do.
He was bit in the snout and leg and they were 2 hrs away from the nearest $600/vials of anti-venom. The vet only had 2 left and the dog wouldn't have made it that far and probably would have needed more than that anyways.
They put him down Rural FL style which is the most humane thing they could have done for him being so far from a vet.
Even though my mom was only 10' away when they came upon the snake, there's really nothing they could have done to avoid it. They were after all in his home. Keep an eye on your dogs fellow TW'ers.