You would have to take the cute and cuddly kitten approach. Our dad never wanted any animals, but we ended up with 30 of them because no one can resist the cute faces of baby animals. Although I think he just now realizes what hit him. It would be better to get kittens anyways because they need to be raised outdoors to have the full cat instinct. Let me coach you through the 'adorable baby animal approach' (works every time.) Step 1: Go get yourself a couple of kittens without talking to your husband first. Step 2: When you bring the kittens home, put the adorable kittens in your husband's lap and make sure you talk with a baby voice about how cute and adorable they are (give them a name too, this will help a lot.) Step 3: Talk dreamily about a mouse/rat free farm and all the good things they will do. He will go on about not keeping them while he is petting the cute and adorable kittens, but I assure you, you have already won and there is nothing he can do about it.