We have water moccasins and copperheads here in North Carolina. Had a horse I was riding bitten three years ago by a medium sized copperhead. Walked him home and administered ice packs. The vet administered antibiotics but no anti-venom. Apparently that is not standard practice for these species. The result of the bite was a 3" round swelling about a half inch thick but no abscess or loss of tissue. In two days there was no sign of the bite. These snakes however are very aggressive. They will come after animals for the fun of it.
I have had four experiences with western diamond backs in New Mexico. While being naturally shy, their bite is not so benign. The immediate adimistration of anti-venom was key as well as the location of the bite in the difference between outcomes.
We lost one gelding to a bite on the nose that swelled the nose shut. Emergency tracheotomy did not help very long as the poison continued to spread and we lost the animal.
The other horse bitten at the same time and location, we were able to catch quicker. We put garden hose up each nostril and administered the anti-venom. The horse lived but with a wicked looking hole in the muzzle.
One horse was bitten on the coronet and treated immediatly. He did fairly well.
One horse was bitten on the fetlock and had so much loss of tissue and continued problems despite anti-venom we had to put him down.
The good thing about diamond backs is that they are not aggressive. Given an opportunity to escape they will take it. When riding in the cool of the day, one has to be more careful. When riding through high brush, make enough noise not to surprise them. For all my time in ranch riding, my contact with the critters were mainly seeing them cross the road at dusk. Easy to avoid.
