so, in this funny little way, the cats contributed to a lower level of violence on that yard. >> vet comes once a month. you can buy dry food and medicine and toys and stuff like that. >> some guys work hard at their jobs to earn their money. and they'll spend it on -- >> sometimes their vet bill is 60, 70, 80 bucks, takes everything they got. >> my baby. >> i wish you cats would get together and get rid of some of the rats we got running around this yard. >> don't want any rats, man. >> the people rats. now you leave the little bitty mice alone. >> we found an even more unlikely bond at california state prison corcoran. >> just like anything, treat it with love and respect, they'll treat you with love and respect back. >> we were just kind of out on the yard shooting. i looked over and saw these guys petting something.