I got my 4 month chihuahua Guapo when he was 6 weeks old. It was too young, I know this but the breeder wasn't going to keep them. He has done great though. The vet can give you some great advice though.. I agree that it is better to wait until the pup is at least 12 weeks but if you get it at 6 weeks old I would suggest talking with your vet to see what advice he/she could give you.