[Sarah Hall]

I have raised over 10 litters of puppies and 5 litters of kittens, yes, bottle-fed them all. As far as the behavioral aspets of this pup being alone, it could either be of no consequence, or could be catastrophic.
Puppies learn how to socialize and play properly during the first twelve weeks of age. If they are denied this opportunity to play, they can develope bizzare,disturbing behaviors such as self-mutilation in order to reduce tension. They will also be poorer learners, have a greater fear of people, animals and noises, and will be shyer and more antisocial. When taking a scientific look at the problem, one has to realize that a pup's communication facilities (sight, smell, hearing, touch) are all nearly at their adult conformation by the time a pup is four weeks old.
If the pup is a female, she will be a poor mother and should not be bred. Dog's maternal behavior is simply more than hormones. The pituitary hormone prolactin can induce maternal behavior but maternal duties (cleaning pups, chewing umbilical cords to proper lenght, etc.) are learned behaviors.
I've got a whole lot more, PM me your e-mail address if you'd like more.
Good luck with the pup (to your buddy).

 

[Sarah Hall]

I've worked as a vet tech, also I am a volunteer puppy/kitten raiser for the local shelter/animal control and rescue groups. Kittens that are way too young are always found abandoned outside vet offices, and most of the pups were victims of bad moms. Three of the litters came from females that were bottle raised and didn't know what to do with the pups, so she decided to eat them in half instead of chew their umbilical cords properly.