12. Border Collie
Coming in at No. 3 on iheartdogs.com's list of the most high-maintenance dogs is the Border Collie. They are often considered to be one of the smartest dog breeds. They are also very active, and because they are so intelligent, they need mental stimulation as well. If you've ever watched dog agility competitions or freestyle competitions, then you've seen lots of Border Collies doing amazing tricks. But unless you're looking for a second career training your dog when you retire, maybe this isn't the breed for you.