How far

I have a hog pen In the middle of my dog's chain dogs on one side and pen dogs fairly close on the other. I also have a pen I will put pups in that's a few feet from another hog pen when the pups are small I will put them in the pen that's close and put several shoats in the pen when I feed I will feed the pigs right by the pups pen and it don't take long before they're going crazy trying to get at them pigs. The other pen I keep bigger hog's in and my chain dogs around it I keep tin around the outside so they can't see the hog's but they smell and hear them all day and night sometimes I will take the tin down and let them bark at the hog's. I don't know if any of this actually does anything for the dogs but mine sure do like hog's and nothing else. I don't imagine that it hurts to have em smelling hog's 24/7.