President John F. Kennedy
The family of President John F. Kennedy vacations in this undated photo. From left: Caroline, first lady Jacqueline Kennedy, John Jr. and President Kennedy. (AP Photo)
After arriving
in Washington from Camp David, Md., by helicopter, President Bush retrieves his black Scottish terrier, Barney, that wandered off to a nearby tree on the grounds of the Naval Observatory, Sunday, April 14, 2002. The helicopter landing site was changed because of the annual garden tour at the White House. (AP Photo/J. Scott Applewhite)
President Ronald Reagan - Rex (King Charles spaniel)
This December 1986 file photo shows first lady Nancy Reagan holding the Reagans' pet Rex, a King Charles spaniel, as she and President Reagan walk on the White House South lawn. (AP Photo/Dennis Cook, FILE)President George H.W. Bush - Millie
This Aug. 24, 1992 file photo shows President Bush, right, and first lady Barbara Bush walking with their dog Millie across the South Lawn as they return to the White House. (AP Photo/Scott Applewhite, File)President Bill Clinton - Buddy
This March 13, 1998 file photo shows President Clinton, center, and first lady Hillary Rodham Clinton with first puppy Buddy as they leave the White House for a presidential retreat at Camp David, Md. (AP Photo/J.Scott Applewhite, FILE)President Bill Clinton - Socks
The White House's first feline, Socks, paws and claws around in the arms of first lady Hillary Rodham Clinton during an East Room event introducing her new book featuring Socks and Buddy, the president's Labrador retriever, Wednesday night, Feb. 3. 1999, at the White House. The book includes children's letters to the first pets and a short history of animals that have roamed the White House in the past. (AP Photo/J. Scott Applewhite)President Bill Clinton - Socks
In this March 19, 1994 file photo, Socks the cat peers over the podium in the White House briefing room in Washington. Socks, the White House cat during the Clinton administration, has died. He was about 18. Socks had lived with Bill Clinton's secretary, Betty Currie, in Hollywood, Md., since the Clintons left the White House in early 2001. (AP Photo/Marcy Nighswander, File)President George W. Bush - Barney & Spot
President Bush and first lady Laura Bush, with their dogs Barney, right, and Spot, left, talk with the media after arriving in Waco, Texas, Tuesday evening, Nov. 13, 2001. President Bush will host Russian President Vladimir Putin at his Crawford, Texas, ranch later this week. (AP Photo/Eric Gay)President George W. Bush - Barney
President Bush does his best to salute while holding his dog Barney as they get off of Air Force One at Andrews Air Force Base, Md., Monday, June 25, 2001. Bush spent the afternoon in Detroit for the annual U.S. Conference of Mayors where he called on the mayors support for more faith-based initiatives. (AP Photo/Susan Walsh)President George W. Bush - Barney
President George W. Bush - BarneyAfter arriving
in Washington from Camp David, Md., by helicopter, President Bush retrieves his black Scottish terrier, Barney, that wandered off to a nearby tree on the grounds of the Naval Observatory, Sunday, April 14, 2002. The helicopter landing site was changed because of the annual garden tour at the White House. (AP Photo/J. Scott Applewhite)