I bought this costume tonight for my dog, but she wouldn’t hold still to take photos, so I thought well I’ll try it on one of my cats. I had to bribe him with treats, and it was too small, the neck part fit good, but he is fat (or fluffy or both), so the Extra Small costume (for my chihuahua) was much too small around his waist. FYI The waist part is not fastened it’s just laying there under him. I would not force something tight or hurt him at all. It’s only fastened at the neck in which he had plenty of room.