We just had to re-home a dog. He was a puppy we had for several months but as he started to mature he became aggressive with out older dog. I think he has some serious alpha. So the pup was spending most of his days in the crate and my son, the nominal owner, wasn't spending enough time with him. I never bonded with him as much as my son, but it still was painful to let him go. But even my son agreed it was best; you have to think about what kind of life the pet is having also.