That's horrible Definitely worth a try with the avoidance training then, I should think. With super tasty treats!
I'm so sorry for that poor friend of yours with her two dogs. That's just horrible. The snake discussion reminded me of something I'd seen a while ago on another dog forum that people were doing in the southwest US: anti-rattlesnake training for dogs. It was a big trend if you hiked with your dog and were "responsible" you'd get this training. I always kind of thought, no thanks, I think I'll just stick to hiking at the beach and the worst we'll get is the odd dead seal. So I just looked this up to see what the training actually was. Eee gads, it involves live "muzzled" rattlesnakes and shock collars. The dog shows interest in a snake, he gets a shock. And there are apparently LOTS of trainers doing this. I'm kind of speechless!
Yes, losing both dogs was an unspeakably awful experience. I do understand why people are motivated to train their dogs to avoid snakes....pity about the methods... With snakes a good recall isn't enough because a dog can find a snake before you realise and snakes are very fast. The best solution for us is avoiding high risk areas.
It must be quite difficult to positively train a dog to avoid a snake. I find a fair few things a bit impractical when it comes to positive reinforcement (that does not mean I use punishment or think anyone else should - I just think you have to find another way round the problem) but having enough snakes safely available to train a default whiplash turn away is just going to be a bit problematic for the average dog owner...let alone proofing it in enough locations!