I was asking a local geothermal dealer (Nebraska) about the possibility of a horizontal loop system for my house and he said that he recommended vertical because "the gophers like to burrow down to the warm tubes and will chew on them". Has anyone ever heard of this? Is this a real issue?

I heard that beavers are bad in a pound loop! 
 I don't know about gophers (like caddy shack) are any different!