Here is a great article for southern Californians about the risk of rattlesnake bites to our dogs.
This is of interest to me because I would not be able to carry my dog out if I were hiking with her and she were bitten. At the same time, I've been avoiding hiking with them because of the foxtails that are so rampant right now, so I've been able to avoid the issue. But if I were to go camping and wanted to hike with the dogs I'd probably get the vaccine a few months in advance.
Enjoy the article.