Many breeds of dogs, cats (including mixed breeds of course) and other animals are found to be not suitable for their present environment, and need to be placed in new, loving, permanent homes. Often they are abandoned by their original owners, separated from them by disasters or misfortune, or run away from a bad situation on their own (abuse, thunderstorms). Often animals are abandoned or given away by their previous owners because they didn't realize how much effort went into caring for them, or a new situation made it too difficult for them to remain where they were (like a baby entering the family, allergies, rapid job changes, etc.)
There is a specialized need in placing Border Collies in a proper home, because their original breeding was to create a dog that could herd sheep in a variety of conditions, and to be tireless and efficient at it. In addition to having this boundless energy, they were also bred to be extremely intelligent and somewhat independent. At times, they need to make their own decisions about what course of action to take, as they might be at quite a distance or out of site of their handler.
If you place a dog like this in a home that can't 'use up' this energy and/or stimulate their minds, what would you expect to get? If you're thinking about what would happen to a human that had these traits, and then they were kept bored and sedentary; yes, you'd have a career criminal on your hands! The same things happen with most Border Collies. That sweet, cute, energetic puppy becomes a mad-dog whose sole purpose in life is to eat the carpeting, chew holes in the wall, dig holes in everything and anything, chew up everything in sight, herd your kids, your cat, the shadows, birds, ceiling fans and even potted plants. They get Neurotic. You may never get to sleep because it is throwing (yes, literally) toys and balls at you while you are trying to go about your usual routine. Just because they are intelligent doesn't mean they can take themselves for a walk or understand that they aren't supposed to pee in the middle of your new afghan or persian rug! They just need to have a job or activity that lets them use up that nervous energy that builds inside of them until they just can't contain themselves, and things get chewed. But, given that a Border Collie is matched with an adopter whose personality and lifestyle match its own, along with an understanding of the particular needs of Border Collies, both can be blessed with each others' company, as they are truly wonderful dogs.
See? I'm obsessed with Calen and BC's!