I live by a lake in NW Arkansas. We have a couple different rattlesnakes, water moccasins, copperheads and coral snakes(I've never seen one).
Local vets do not have/keep anti venom...as far as I know. The neighbors dogs that have been bit got IV's and anti biotics...maybe steroids. They've all survived that I know of. Cats that were bit all died.
I've read that Benadryl doesn't do anything for snake bites but I have it in my truck. I also get my dogs rattlesnake vaccines. I know some say they do nothing as well but they are relatively cheap and if nothing else...it makes me feel better.
When I am out of town on longer hunting trips, I have a file with my dogs shots, medical history etc., in my truck and I find a local vet and give them my dogs information....before I need their services. I've had emergencies with my dogs and answering questions and getting them medical records....takes time. I also load the vet address into my GPS so I don't waste time trying to find their building. I hunt by myself most of the time and I bought a Final Rise vest last year so I can put the dog in my vest to immobilize them and carry them to the truck, as quickly as possible
I think being organized, not wasting any time and getting them to a vet as soon as possible is about the best thing we can do for our dogs that have been bit or hurt.