6...

IF toys can keep their head when all about you
Are losing theirs and blaming it on chew,
If you can lick yourself where all men can’t do,
And making friends you lick them too;
If you can whine and not be tired by whining,
Or being dragged about, in collar and ties,
Or being petted, don't give way to shaking,
And yet don't look too thin, nor bark at flies:
...
Yours is the furr and everyflea that's in it,
And - which is more - you'll be a dog, and run!