• 1 of 13

    President Obama rings in his 51st birthday at the White House this weekend, and we can't imagine anyone who's more excited to celebrate than his best friend, Bo. We're sure Mrs. Obama and the girls have got big plans for the birthday, but let's be honest: the guy who knows how President Obama wants to party best is the Portuguese Water Dog himself. If you don't believe us, check out the photos they've taken over the years. Bo always brings a big, silly smile to President Obama's face. To wish the 44th POTUS a happy 51st, we've rounded up our favorite photos of the power duo.

  • Win McNamee/Getty Images
    2 of 13

    THE FIRST SON

    When Bo was adopted into the first family, he wasn't considered just a pet, but also a son. During an appearance on "The Late Show" with David Letterman, Mrs. Obama confessed, "He is my son. I have two girls and a boy." 

  • 3 of 13

    PARTY ANIMAL

    Bo always has a lei stashed somewhere in case of an emergency luau. After all, his owner hails from Hawaii. 

  • Win McNamee/Getty Images
    4 of 13

    BO BUOYANCY 

    Even after a long day dealing with international affairs, President Obama can always rely on Bo to reenergize him. 

  • 5 of 13

    PRINCELY PUP 

    The real king of the house? We think it's pretty obvious.

  • 6 of 13

    VERY IMPORTANT PUP

    President Obama never forgets to introduce Bo to his most important guests. 

  • 7 of 13

    LOOKING GOOD 

    Everyone in the first family has to always look their best, and Bo is no exception. His regular grooming appointments keep his curls extra bouncy. 

  • Saul Loeb/AFP/Getty Images
    8 of 13

    CUTE CHECK-UP

    No matter how busy President Obama may be, he always stops by to ask Bo how he's doing. 

  • Roger L. Wollenberg-Pool/Getty Images
    9 of 13

    CANINE COMPANION

    Bo accompanies the President and Mrs. Obama at their most important events, including the book reading at the annual Easter Egg Roll. 

  • 10 of 13

    HAPPINESS IS ...

    President Obama loves nothing more than taking a walk with his entire family. 

  • Kevin Dietsch-Pool/Getty Images
    11 of 13

    PERSONAL SHOPPER 

    President Obama doesn't like to send anyone else out to shop for Bo's things. He prefers bringing Bo to the store so the dog can pick out what he wants for himself. 

  • Gary Fabiano-Pool/Getty Images
    12 of 13

    UP CLOSE AND PERSONAL 

    Bo is the keeper of President Obama's most intimate secrets. The president won't ever have to worry about Bo telling anyone though; he's as loyal as can be! 

  • 13 of 13
    Next: Hottest Celebrity Dog Dads!

    SO HAPPY TOGETHER 

    There have been many presidents and first dogs who have run through the White House's halls, but we don't think any of them shared a closer bond than President Obama and Bo.