When I was growing up, someone told my mom to give the dogs a penny to worm them. I think back then, they were probably all copper, and not zinc in the middle. My mom would make hamburger meatballs and line the dogs up very month or so for their penny treatment. Since they were all there and didn’t want any other dog to get their meat ball, mom would toss and the dog would grab and swallow as fast as he could. they never knew that there was a penny inside of that meatball because they never chewed it. Whether it worked for the worms or not, I am not sure, but our dogs were always healthy and didn’t have worms as far as I know.