I have outside feral cats. After the spay and neuter and shots they will never be trapped again, unless I see something unusual happening to one of them. If they turn up hurt or something on that order, I will try and trap them again to address the problem. But my question is, is there anything that I can give them to prevent maybe some health issues in the future. Is there any over the counter, or medicine that I can put into there food to help them out. I do notice sometimes someone might vomit, not often. But I just thought I could prevent some health issues with them if I could do something else for them. It also would have to be something that doesn't harm them. Not sure what cat eats what so who is to say they all got the medicine. Any comments would be appreciated.