In short order, Teddy -- a bright-eyed and bushy-tailed 3-year-old yellow Lab -- punched a wall button with his nose, yanked a rope to open a kitchen cabinet door and tugged a walker across the floor.

In short order, Teddy—a bright-eyed and bushy-tailed 3-year-old yellow Lab—punched a wall button with his nose, yanked a rope to open a kitchen cabinet door and tugged a walker across the floor. After ...