@boomerang,
The only dog we had that would even remotely support ehBeth's theory of attachment was a fourteen-year-old dachshund whose owner had to move to a retirement home that didn't allow dogs. When she was eight years old, we had taken care of her during a vacation. Everything had gone wonderfully. But now she was fourteen, extremely frustrated about being separated from her pack, her body language signalling sorrow and misery all the time.
Unsurprisingly, her behavior was awful. She refused to walk, refused even her favorite foods, refused to defecate or urinate in the garden, took her business inside instead, and did it consistently in places where it would bother us the most. When we told the old owner of her suffering, his sister in law eventually volunteered to take her in. From one moment to the other, everything was fine again. Apparently, the sister in law had the right pack smell.
So, my opinion would be much closer to ehBeth's if the dog in question was 14 years old. But 16 weeks? I just can't see how that would raise pack-attachment problems.