I enjoy taking Winnie on hikes in the Angeles National Forest from time to time, and we normally stick with the cooler months (late October to April) for most of our hikes, due to Winnie's collapsing trachea. And, it's just not so much fun when it's too warm out there. Hiking in Southern California is actually very fun; there's a lot of great terrain and it's amazing that not too far from the city (about an hour away), you can really find yourself relaxing in the mountains - off-leash & far away from cars and civilization.
We've run into critters like squirrels, chipmunks, an occasional deer. And, just a few weeks ago (our usual hiking group without me and Winnie) came across a rattlesnake. In fact, they got a little off of the trail, and our friend who was in the front of the group nearly stepped on a rattlesnake. Luckily, Winnie was not there - as we opted not to go that day. However, there's no doubt that if we were there, Winnie would have been bit.
Just a week ago, I was notified about an upcoming Rattlesnake Avoidance Clinic, so we signed up and went this morning. I was a bit apprehensive since they were going to use shock collars and Winnie is so head shy about collars anyway. It took some work, since she managed to get loose. And, after a quick chase around the park, we finally had her setup in her harness and a shock collar on the lowest setting.
The trainers go in a dog park with her (without me). Inside the dog park are two small cages with rattlesnakes in them. On a leash, they take her close enough to sniff the snake at first but when she goes in too close - they gave her her first zap! Meanwhile, the snakes rattles are going full speed. (See picture below, it was taken right before the first zap.)

She didn't like that first zap... There was a lot of Shiba screaming and drama going on after this.

She was happy to walk away from the snakes!

The lesson was only about 15 minutes, but she was not having any fun whatsoever. Here's a shot of Winnie letting them know that she wants OUT of this exercise! It sure didn't take her long to learn that the snake is not something to be near.

At the end they took her to one end of the dog park, and let me enter. Then they take her off leash and have me call her. She didn't want to come to me at first, because she knew there were snakes there. But, she decided to walk the perimeter, and came over to me by walking as far away from the snakes as possible. She passed with flying colors.
The trainers recommended coming back to rattlesnake avoidance training again next year - just to be sure that the training has taken "effect". They said that with most dogs, two to three repeat lessons are the most effective. However, they have seen cases where some dogs come back year after year not retaining anything. I doubt Winnie falls in that category. It only took her 3 zaps to learn that snakes are not cool to be around.
For some background on rattlesnake bites in dogs, there was a study compiled by the American Veterinarian Medical Association -
http://avmajournals.avma.org/doi/abs/10.2460/javma.2002.220.1675The UC Davis Veterinary Medicine "Pharm News" has a rather extensive write up on animal medicine in relation to rattlesnake bites. For their write up -
Vetmed.ucdavis.edu