He is arthritic, deaf and blind, but Queensland quarter horse Calypso has almost doubled the average life span for its species.

Key points: A Queensland gelding named Calypso is turning 50 today

A Queensland gelding named Calypso is turning 50 today Equine expert Rhian Partridge says most horses die between 25 and 30

Equine expert Rhian Partridge says most horses die between 25 and 30 She put Calypso's longevity down to "good genes" and hanging onto its teeth for a long time

The gelding turns 50 today, the day all horses in Australia have their birthday.

Despite his ailments, Calypso, who lives on an agistment property at Tallebudgera on the Gold Coast hinterland, is a happy horse, according to his carer, Jenny Dyson-Holland.

"He's got a will to live," Ms Dyson-Holland said.

"You'll get some people say 'Why do you let a horse get to that age?'. But he has very limited arthritis, he's in no pain, he eats all of his dinner, and he just loves life.

"So why change it?"

'He's been through ups and downs'

Born in 1969, the horse was used at a riding school when the Nakic family saw him being mistreated in the 1970s.

An old image of Calypso the 50-year-old old quarter horse (left) with his former stable mate, Misty. ( Supplied: Eva Nakic )

They bought Calypso and gave him to their daughter, Marie Nakic, who moved the horse to Queensland in 2004 when the family relocated.

He lived on the family property at Biddaddaba, near Beaudesert, until he was moved to the property in Tallebudgera 12 years ago.

Jenny Dyson-Holland said Calypso has never kicked or bitten anyone.

50-year-old Calypso with his carer Jenny Dyson-Holland at a property in the Gold Coast hinterland. ( ABC Gold Coast: Tom Forbes )

"He does have trust issues, but on the other hand he is pretty much totally blind. He has very, very limited hearing," Ms Dyson-Holland said.

"He's been through some ups and downs. He had colic once in his life.

"He's a tough little guy."

It's all in the genes, says vet

Equine veterinarian Rhian Partridge said it was very unusual for a horse to live to 50 years of age, which in human years was 150.

"It has done amazingly well to get to this age," the Gold Coast-based vet said.

"Just like with people, it's obviously got good genes.

"It's obviously been well cared for throughout its lifetime and I would probably say that it is very fortunate that it has probably held onto its teeth for quite a long time."

Calypso has lost his front teeth and lives on a diet of horse feed that has been moistened into a mush.

Gold Coast-based equine veterinarian Dr Rhian Partridge said it is highly unusual for a horse to live for 50 years. ( ABC Gold Coast: Tom Forbes )

"Ponies tend to live a little longer, so we tend to see them living into their 30s, but to get to 50 is pretty phenomenal," she said.

Dr Partridge said most horses died before between 25 and 30 years of age.

Although Calypso is in good health, Dr Partridge said his days were numbered.

"Through general probability it's unlikely that it's going to be living until it's 60, otherwise it seriously will be a Guinness world record book horse," she said.