The answer is YES - you can teach a dog to avoid the danger of snakes using positive reinforcement. By making caution and avoidance the dog's choice, you run a much lower risk of side effects and can have much more robust results.

To begin just simply place the snake right out in the open where your dog can see it. If he immediately goes toward it, use the training collar to deliver a static correction so that he recognizes right off hand that snakes are bad. Just one momentary correction should work just fine.