The weather has finally gotten warm and now it is time to get outside and enjoy our beautiful outdoors with your best four-legged friends. As you are ambling along the path in Ute Valley park you hear from under a pile of nearby rocks that unmistakable rattling noise which causes the sensation that Emily Dickinson so aptly described as "zero at the bone". Your dog's response to the rattlesnake, however, is "Hey, that looks interesting. How 'bout I go poke my nose at it.". Before you get a chance to react you have a yelping dog with a rapidly swelling snout. What should you do?
Before you feel the need to further harass the snake you might want to keep in mind that one victim is usually completely sufficient for the situation. In other words, a snakebite for both you and your dog will not enhance your enjoyment of the emergency, so leave the dang snake alone.
At this point John Wayne would probably produce a large Bowie knife and start carving away at the bite wound in order to make a big enough opening to suck the poison out. In reality this only increases the pain and trauma to the area. The other reality is that even the sweetest golden retriever may be induced to forcibly remove your lips from your face if you start slurping away at that very painful wound, thus violating the only one victim per emergency rule. As hard as it is to not DO something, the best thing you can do is leave the snake bite alone and get the dog to a veterinarian. If you can carry your dog that would be best, but the 120 pound mastiff will probably have to hoof it on his own. On the way back to the car you can calm yourself with the knowledge that even if you did absolutely nothing for the dog from this point on it would be very unlikely that he would die from the snake bite, even if he is an itty bitty yorkie.
At the veterinarian's your dog can get good pain management, antibiotics, and supportive care. Some veterinarians will have antivenin on hand, but if not it can usually be procured from a human hospital if needed. Antivenin is expensive, and there is a small risk for adverse reactions, but it can take a rattlesnake bite that would result in weeks of severe pain and suffering and turn it into a few days of swelling and tenderness at the site in a dog that is otherwise doing well. It can be absolutely lifesaving in the more serious cases of envenomation.
Recently a vaccine for rattlesnake bites has been created. It is given as a shot like other vaccines then boostered in two weeks, then repeated yearly before summer hiking season. The vaccine stimulates a dog to produce antibodies that help neutralize rattlesnake venom. Vaccinated dogs should still be seen by a veterinarian if bitten, and may still require antivenin, but what would have been a severe reaction may be reduced to a moderate one, and moderate reactions become mild. In my limited experience with the vaccines I have found that they have a higher rate of adverse reactions when given, especially pain and swelling at the injection site, but have been mostly well tolerated. I have not personally had a patient put the vaccination to the test with a snake bite, so I can't tell you how well it works in practice. You will need to weigh the risk of adverse vaccine reactions against the anticipated rattlesnake exposure when considering getting the shots.
In Tuscon, where rattlesnake bites are common, there are training programs that can teach your dog to leave the snake alone. This employs another basic truth about emergencies which is that the best way to deal with an emergency is not to have one. Out here snakebites are fairly uncommon, so there are no established rattlesnake aversion programs that I am aware of. Instead, a leash and some extra vigilance when in rattlesnake country goes a long way toward preventing some of the unintended consequences of overzealous nose poking.