Puppies and kittens should be bought or removed from their mothers at 6 to 8 weeks of age. Under 6 weeks they are too young to leave their mothers, and after 12 weeks you have missed the very important 'sensitive' period in their life when good lifetime habits can be initiated and the animal will learn to respond to human contact.
When you're picking up a puppy or kitten that you've bought from a breeder, take a soft piece of fabric with you. Rub it on the fur of the animal's mother and siblings to pick up their scent and put it in your new pet's bed.
If your pet cries at night, it may still miss its mother. Wrap a ticking clock in a towel and put it in the animal's bed. Or put a well-wrapped hot-water bottle in its bed for it to cuddle up against.
If possible buy two puppies at the same time; they'll have each other for comfort and company.
