My housecat came into the brooder with me all the time, but I wouldn't trust her alone with chicks. The barn cats are generally ambivlent about the hens, but they are segregated. You could use the neighbour's cat to patrol the coop so long as the cat can't get to your birds. Providing a little cat kibble for surrounding cats is not always a bad thing, it encourages them to patrol but keeps them from being ravenous. Even a well-fed cat will hunt rodents. I have 18 cats who are regulars around the barn/coop at this time. No losses, but they don't have direct contact either.