they'll find the salt one way or the other, most ground in the US, if not all, has salt in it, and they drink the water, which gives it back to them,just like every other animal in the world....but above it was mentioned how they like to lick the sweat off of people to get it and thats one way to help them not do that, is by putting a salt block around so they get plenty. I have never heard of them taking to much from a salt block and harming themselves.... I live in michigan/detroit ...we have ALOT of salt here in our soil (detroit salt mines are huge) and the worlds largest limestone deposits. no problems that I know of.