Donald Trump's celebration this week of Conan — the military dog involved in the raid on Islamic State leader Abu Bakr al-Baghdadi — is a marked change from the way the US President usually talks about canines.

Key points: Donald Trump is the first US President in more than a century not to have a dog

Donald Trump is the first US President in more than a century not to have a dog He has previously said he doesn't have time to look after a pet

He has previously said he doesn't have time to look after a pet Beyond dogs, former presidents have had pet raccoons, lion cubs and sheep

"AMERICAN HERO!" Mr Trump said on Twitter, accompanied by a photoshopped image of the US leader placing a Medal of Honour around the now-famous Belgian Malinois.

But a search of Mr Trump's use of the word "dog" in his previous tweets shows that when he's talking about canines, he's rarely doing it nicely.

The president often mentions people being "fired like a dog", "dumped like a dog", and "dropped like a dog".

And while Mr Trump has lived with at least one dog before becoming president — his ex-wife Ivana Trump's poodle called "Chappy" — Ivana has previously written that the two did not get along.

So it may not come as a surprise then to learn that unlike the majority of US Presidents, the position of First Dog — or "FDOTUS" — is currently vacant.

In fact, Mr Trump is the first US leader in 118 years to not own a dog while in office — but his lauding of Conan has drawn attention to the White House's quirky history with resident pets.

So why does Mr Trump not have or want a FDOTUS? And how does his dogless administration fit in with the odd lineage of peculiar pets that have stood beside many of America's historic leaders?

Why is there no FDOTUS?

President Barack Obama plays with Bo, the Obama family dog, aboard Air Force One during a flight to Hawaii, in 2011. (Official White House Photo by Pete Souza) ( Supplied: The White House/Pete Souza )

Mr Trump addressed this issue directly at a rally in El Paso earlier this year, saying he "wouldn't mind having" a dog but that he didn't have the time — and besides, he thought it would look "a little phony".

"How would I look walking a dog on the White House lawn?" he asked his supporters.

"Feels a little phony to me. A lot of people say 'oh you should get a dog … it's good politically' … that's not the relationship I have with my people."

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The Trumps have never officially owned a dog while in office as the First Family, although there was some talk in 2016 that they had been offered a puppy by a supporter from Florida.

The puppy was a "goldendoodle" — a golden retriever crossed with a poodle — and Donald Trump reportedly asked that it be shown to his son Baron.

But there was no official word on whether Patton ever did become a member of the Trump household, nor whether the dog would live in Mar-a-Lago or the White House.

This means that President Trump joins only presidents James K Polk (1845–1849) and Andrew Johnson (1865–1869) as officially not having any pets during his term in the White House, at least so far — although Andrew Johnson is known to have fed a family of white mice during his impeachment.

It's a contrast to his immediate predecessor Barack Obama who had two Portuguese water dogs named Bo and Sunny, and was frequently pictured with them.

Bill Clinton with Socks the cat in 1993. ( Wikimedia Commons )

George W Bush also had two dogs — two Scottish terriers named Barney and Miss Beazley — while Bill Clinton had a chocolate labrador named Buddy and a cat named Socks.

Rebecca the raccoon

There have been an abundance of dogs and cats, sure, but there have also been chickens, bears, snakes, cows, squirrels and plenty more unlikely animals to call the White House home.

Rebecca the Raccoon was originally destined to be Thanksgiving dinner for President Calvin Coolidge and his wife, Grace Coolidge.

She came from Mississippi in 1926, but the Coolidges took a liking to her and decided to keep her as a pet instead.

Grace Coolidge with her pet raccoon Rebecca in 1927. Grace was the wife of former US president Calvin Coolidge. ( Library of Congress via Wikimedia Commons )

In one of his press briefings, President Coolidge asked for help in naming the raccoon, and Rebecca would appear with Lady Coolidge at the annual Easter egg rolls at the White House.

She was reportedly allowed free rein inside, and according to Lady Coolidge her favourite activity was playing with bars of soap in the bath.

She was given a mate, Reuben, who promptly ran away, and Rebecca herself was gifted to the Washington Zoo after one-too-many daring escapes.

Calvin and Grace Coolidge, with their sons Calvin Jr and John and a pet dog. ( Library of Congress )

When Mr Coolidge's successor Herbert Hoover took up residency at the White House, Rebecca's enclosure became home for an opossum called "Billy Possum", who was once loaned to a high school athletic squad after their mascot went missing.

While Rebecca may have been a favourite, the Coolidges were one of the most prolific pet-owning First Families, and among plenty of cats and dogs they also had a wallaby, a donkey, a goose named Enoch, two lion cubs called Tax Reduction and Budget Bureau, a pygmy hippo and a black bear.

Many of the more exotic animals were given to them by overseas dignitaries and businessmen, and most were gifted to places like the National Zoo.

A pair of lion cubs, given to president Calvin Coolidge as a gift, photographed in 1927. ( Library of Congress )

An earlier President, Martin Van Buren, was given a gift of two tiger cubs from the Sultan of Oman shortly after he became president in 1837.

According to the Presidential Pet Museum, Van Buren wanted to keep them at the White House, but he was foiled by Congress, and the cubs were sent to the local zoo instead.

Woodrow Wilson's sheep

Sheep munch on the White House lawn in 1919. ( Library of Congress via Wikimedia Commons )

Most famous among Woodrow Wilson's animals at the White House was a flock of sheep that kept the grass short.

He brought them in during World War I to keep grounds keeping costs down and free up the gardeners to contribute to the war effort.

The wool from the sheep was also collected and auctioned off to help the war effort.

Among the flock — which numbered up to 48 sheep at one point — was Old Ike, a ram that liked to chew tobacco and cigar butts and attack members of the White House staff.

Josiah the badger from Kansas

Theodore Roosevelt's family had a menagerie of animals, including cats, horses, snakes, a flying squirrel and a lizard named Bill.

Archibald Roosevelt, a son of Theodore Roosevelt, is photographed between 1903 and 1905 with one of the family's many pets, Josiah the badger. ( Library of Congress )

Like the Coolidge family, President Roosevelt was often gifted exotic animals from overseas, but he also collected pets from his travels across the country.

One pet was Josiah the badger, who is believed to have come from Kansas when the President was visiting on a railroad tour.

The story goes that a 12 year-old girl offered a baby badger to the president, who named it Josiah.

Josiah was a beloved pet at the White House and even had his own special enclosure which allowed him to dig burrows without escaping.

But he also had a tendency to bite and was eventually given to the Bronx Zoo where the First Family continued to visit him.