President Harry S Truman once advised that 'if you want a friend in Washington, get a pet'.

But president-elect Donald Trump has proved he's determined to forge his own path and could be the first commander-in-chief in a century to lead without a four-legged friend at his side.

Before Trump, Andrew Jackson was the last president to not own an animal.

If Trump goes his entire presidency without a pet, he will be only the third after Jackson and James K. Polk.

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President-elect Donald Trump could be the first commander-in-chief in more than a century to not have pet in the White House

When president Obama was elected, he kept the promise to his daughters Sasha and Malia that they could have a dog in the White House

After searching for a dog that wouldn't aggravate Malia's allergies, the first family settled on a Portuguese water dog named Bo. In 2011, they would add a dog named Sunny to the family

Presidents have owned conventional pets like cats and dogs, and more exotic animals like bears, tigers and pygmy hippopotamus, AOL reported.

Pets help soften a president's image and a big part of their job is posing for photos with the commander-in-chief.

A pet could help boost Trump's low likability ratings.

When president Obama was elected, he kept the promise to his daughters Sasha and Malia that they could have a dog in the White House.

President George W Bush had a Scottish terrier named Barney (left), who had a website and would run around with a camera on his neck dubbed 'Barneycam'

Bush also had a terrier named Miss Beazley. President Bush carries his dog Barney as Fist Lady Laura Bush holds Miss Beazley

President Bill Clinton had a chocolate Labrador Retriever named Buddy, who helped is said to have helped him get through the aftermath of his affair with Monica Lewinsky

President Clinton and Hillary Clinton let children pet Socks the cat at a Christmas book reading

After searching for a dog that wouldn't aggravate Malia's allergies, the first family settled on a Portuguese water dog named Bo.

Later, in 2011, they would add another Portuguese water dog named Sunny to the family.

President George W Bush had a Scottish terrier named Barney, who had a website and would run around with a camera on his neck dubbed 'Barneycam'.

President Bill Clinton and First Lady Hillary Clinton had a chocolate Labrador Retriever named Buddy, who helped is said to have helped Clinton get through the aftermath of his affair with Monica Lewinsky.

President George HW Bush (left, with Barbara Bush, right) had an English Springer Spaniel named Millie (center) who was credited with 'writing' 'Millie's Book', which became a best seller

Boris Yeltsin, President George HW Bush and Barbara Bush stand on the lawn in front of the White House with Millie

President Ronald Reagan presents First Lady, Nancy Reagan, with an early Christmas present of a king charles spaniel named Rex

The Clintons also had a cat named Socks.

President George HW Bush had an English Springer Spaniel named Millie who was credited with 'writing' 'Millie's Book', which became a best seller.

While most presidents had a single cat or dog, President Ronald Reagan opted for a menagerie of dogs and horses.

They included Lucky, a Bouvier des Flandres, Rex, a Cavalier King Charles spaniel, Victory, a golden retriever, Peggy, an Irish setter, Taca, a Siberian husky and Fuzzy, a Belgian sheepdog.