I have Miniature Pinschers, they are bred to kill rats. but just about any dog will kill rats, I have mutts that do it. but as they say, they will also kill your chickens if given the chance. just how allergic go cats is your hubby?? Barn cats, that live in the barn should not be a problem if he isnt petting them. barn cats should be fed cat food and left to live in the barn, they know their jobs and do it well, mine kill weasels and rabbits along with mice, moles, and other small vermin. Someone on here posted that they started locking their cat in the run at night when chickens were locked in the coop. I think thats a great idea!
Change your rat poison, find the better ones that are aimed at warfarin resistant rats.
you can also blow them up lol, google the rodenator and watch how that works. fill the tunnels with propane and then ignites it, blows them right out of the dirt. I want one.....