There's a long legacy of presidential pooches like the three we just mentioned. But the human occupants of 1600 Pennsylvania Avenue haven't always limited themselves to dogs.
We're talking about lions, tigers and bears, oh, my, also horses, elephants and -- hippos ? Can you imagine bringing a pet hippo into the White House?

Can you imagine bringing one anywhere? We're going to let Tom Foreman handle the history of presidential pets.

Ever since George Washington, presidents have been judged by the dogs they run with.

Presidents and their pets have a long and storied history.

Garrett Graff is editor in chief of "Washingtonian" magazine.

Most of us don't get the intricacies of Middle East oil politics and the rise and fall of the GDP. But we can get if you connect with a dog.

Presidents have kept company with critters of all types. Theodore Roosevelt turned the White House into a zoo with parrots, horses, ponies, bears, a zebra, snakes and, inexplicably , a one- legged chicken.

John Quincy Adams actually used to love surprising guests in the White House with an alligator he kept in a bathtub .

William Taft had a cow. Woodrow Wilson pioneered the PR potential of sheep, using them to trim the White House lawn during World War I and apparently calling someone about it.

Calvin Coolidge, like Roosevelt, had it all, lion cubs, a goose, a bobcat, a raccoon and a pygmy hippo named Billy.

Both Teddy Roosevelt and Calvin Coolidge gave large parts of their menagerie to the National Zoo here in

Washington. Even today, many, if not most of the pygmy hippos in zoos in the United States are descendants of that original Calvin Coolidge hippo.

But dogs have always been the most likely pick for first pet, for better or worse. For example, there was a story going around that during a tour of the Aleutian Islands, Franklin Roosevelt left his Scottish terrier, Fala,behind, and sent the Navy back to rescue him.

Almost every president has had at least one dog and maybe -- just maybe -- there is a reason beyond politics.

The presidency is a very lonely undertaking. I think there are very many moments in the White House where what you really want to do is take your pet for a walk.