Snake Avoidance Training

[StarryNite]

I live in an area where snakes do come into our yard. Mostly they are bull snakes but occasionally we do get rattlesnakes. I'm thinking of taking our dogs for snake avoidance training but I'm not sure how effective it is. My neighbor took her Mastiffs to be trained a few weeks ago. Last week I went back with her for the retest to see if the dogs remembered what they had learned. I wasn't particularly impressed. The first time she walked them past the snake neither one of them even seemed to notice it let alone alert her of it's presence. And there was a terrier who was back for a retest that when walked past the snake not only noticed it but wanted to attack it. After being shocked again the next time past it skirted the snake. But what about a month later if it notices a snake in it's yard? Will it remember the shock or will it act on instinct and attack it?

I don't know if these dogs are in the minority with their reactions, or lack thereof, or if snake avoidance training generally just doesn't work. Does anybody have any experience with it or know anything about it? I would really appreciate any feedback.