When he was tiny we're talkin' like 5 lbs he was in a cat carrier. Then he was sweating in there so bad that I went and bought him the one that is 2 sizes up from that. It's not very big. He can lay out and touches from front to back that's it. He can stand up and don't quite touch the top yet. I thought about putting him in w/ his mom to see if that would help. Where there is 2 dogs together but hers is a big training wire type kennel. So, afraid to do that cuz then there's all kinds of room in there. But, yes I made sure not to get to big for that reason but it don't seem to work.