In my opinion, if the puppy doesn't start eating, and soon.... you should take the puppy to the vet. I've raised several litters of puppies, and never have I came across an 8 week old puppy that won't eat, unless there is some type of health related issues going on. My suggestion would be to take the puppy to the vet ASAP! Also, you should contact the breeder, as they may have some information that you or your vet may find helpful.
Best of luck!

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Some people say dogs are man's best friend,
Some say their dogs are a huge part of their lives....
My dogs ARE my life,
They are my heart & soul.
The greatest friends i'll ever know....