Did you know what dog breed is the smartest? according to www.petmedsonline.org, the smartest dog is the Border Collie. Like many intelligent breeds, the Border Collie needs a job to do. If they don’t have a purpose in life or some kind of job, they will not be happy. Border Collies should definitely not be left at home alone all day, and if they are, they can become quite destructive. They need constant companionship, praise, and extensive exercise. So if you work and live in the city, a Border Collie probably isn’t the dog for you! Because of their legendary intelligence, Border Collies set the standard in competitions for such skills as agility, obedience, and of course, sheepdog trials.