Thomas Jefferson had more than thirty pets including two grizzly bear cubs. They were a gift from the explorer Zebulon Pike. The bears didn't stick around long as Jefferson saw fit to send them to a museum in Philadelphia
John Quincy Adams kept a pet alligator in the East Room of the white House. It slithered around and chased visitors. He also had silkworms
Andrew Jackson kept fighting cocks. No word if he had any cock fights at the White house
Martin Van Buren kept two tiger cubs for a short time
The Lincolns let their sons Willie and Tad keep their pet goats in their rooms. They also had dogs, a rabbit, a horse, and a turkey
Andrew Johnson fed the white mice he found in his White House bedroom
Benjamin Harrison had a goat, a collie, and two opossums he named Mr. Reciprocity and Mr. Protection
Teddy Roosevelt's brood brought a veritable zoo to the White house. Their animal retinue included badgers, mice, raccoons, pigs, parrots ,dogs, cats, baby bears, snakes, a one legged rooster, a kangaroo rat, and a Shetland pony named Algonquin plus a spotted Hyena that Roosevelt taught tricks and let beg for scraps at the dinner table.
William Taft had two cows, Mooly Wooly, and Pauline Wayne, At least one of them lived in the White house kitchen, Taft liked his milk REALLY FRESH!
Woodrow Wilson kept a herd of sheep that he let graze on the White House lawn. He also had a ram named Old Ike that liked to chew tobacco.
Calvin Coolidge had Rebecca and Horace, raccoons, Ebenezer the donkey and Budget Bureau, lion cubs, Billy, the pygmy hippo, several dogs, canaries, a wallaby, a small antelope and a black bear.
Herbert Hoover one upped John Adams by bringing two crocodiles to the White House!