I had a rattler in my barn earlier this year, I tried to get him out when it was cool but he wouldn't reveal himself to me then. Later in the day after it got hot I went in (after my dog) and my dog had him mad and rattling in a hurry. 20 gauge seemed to be very effective on him. Since then she has revealed to me one more snake in the yard...she is a lab that constantly runs the yard looking for rabbits, so when she was sniffing around the wood pile a mama rattler took offense to her hunting routine and then came in contact with my rake. Similar thing happened last summer in the garden, dog was snooping around her hunting spots and got close enough to make one mad/rattle. So...my dog seems to make them mad/rattle and then I know they're around . All 3 times I don't think I would have known the snakes were around if it wasn't for her. She also knows to get back when she hears the rattle though, where some dogs may not known the danger. She also is up to date on her rattler vaccines. I'd rather send a dog in first to find the snake then follow behind for a clean up kill.