Leaving its mother and litter mates can be a traumatic time in the life of any puppy - and traditionally it tends to take place between six and eight weeks, when the puppy's instincts to make friends with strangers overcomes its natural wariness. 

But a recent Italian study has found that dogs which leave home before they are eight weeks old are significantly more likely to display problem behaviours as adults.  These findings echo another study with German Shepherds which showed that puppies removed at six weeks showed appetite loss, increased distress and susceptibility to illness, while those left until they 12 weeks old were healthier, both physically and mentally.

Perhaps we need to look again at the optimum age for removing a puppy from the litter.  But in all this talk of age, we should not lose sight of the importance of the quality of the environment.  It is probably much better to remove a puppy at six weeks - or even less - from an impoverished environment; similarly a puppy in an exceptionally rich environment where the owner is prepared to start initial training and  introduce it to all kinds of new experiences may benefit from staying twice as long.