Dog's killing stray Cat

I have the exact same situation. Our shop is right beside the neches river though and people drop cats off down there everyday that they don't want anymore. They come straight to our shop because we have a HUGE dumpster full of food. Most of the guys that work for us bring their garbage to work and throw in our dumpster so it gets raided by coons and cats every night. My dogs get so excited when I'm 2 miles from the shop that they start whining and going crazy. They spend the entire day cat and coon hunting. In 5 years they've killed atleast 100 coons and cats out there. Whenever the dumpster is empty the coons will jump in there and can't get out and I'll throw a board in for them to climb out. It's hillarious watching my dogs. My older cur will grab them by the tail or back legs and start spinning and hit their heads on the side of the shop. It doesn't kill them but it sure is funny.