I understand that when Ralphie has seen cats he's tried to chase them. He's not a mean guy at all so I don't think he would ever hurt one. I think he's just really curious and wanting to play. I imagine if a cat put him in his place he'd back off. I don't have any cats though so I don't have a way of testing this.
When Ralphie came to the rescue he had some red spots on his skin. It was determined to be Demodex which is a non-contagious form of mange. It's actually common and again..not contagious. The rescue tried to beat it with natural remedies but that didn't work so he was put on the traditional meds which took care of it. The medication is Ivermectin, the same ingredient in heart worm pills, and it costs about $20. He's got some spots on his body where the hair is a little thin...but it's all there. If someone didn't tell you about it you probably would never notice it. He's over this hurdle now and looking for his forever home. Don't let his past prevent you from thinking about opening your home to his great guy. He's got an A+ personality and would do well in any home. I'll tell you that I made an appointment at the groomer for him and I mentioned that he'd had this in the past and the groomer was not concerned in the least. While we may not hear of it much in IL and WI, it's not uncommon. It can affect dogs who have been poor living conditions. We've got Ralphie on a high quality dog food diet now to make up for his past and to keep him healthy!