How old can a pup be to leave its mom?

A chihuahua puppy can leave there mother at 5 weeks old as long as there healthy and eating well. I have had 6 Chihuahuas and I have took them all at 5 weeks old. My chihuahua had a litter of puppies and they started eating soft dog food at 4 weeks old. Everyone says a puppy shouldn't be taken from its mother until 6 to 8 weeks. That is not true at all. Every dog I have ever had has been taken at 5 weeks and they are very healthy. Some people also say if you take a puppy that early it causes problems with them biting and playing. That is also not true. So as long as a puppy is eating good it CAN be taken from its mother at 5 weeks of age...