A horse believed to be the oldest in the world has died after reaching the age of 51.

Shayne, a liver chestnut Irish Draught cross thoroughbred, had been enjoying a comfortable retirement at an Essex sanctuary, spending up to five hours a day in the fresh air despite suffering from mild arthritis.

But last month he was unable to get back up after his legs gave way and staff took the decision to put him down.

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Shayne, pictured with stable hand Paige Emmins, had mild arthritis but still enjoyed the fresh air

Shayne, a liver chestnut Irish Draught thoroughbred, has died at the age of 51 at an Essex sanctuary

Sue Burton, founder of the 40-acre Remus Memorial Horse Sanctuary, near Ingatestone, Essex, said: 'Shayne was a happy horse, a lovely old boy and we are proud to have known him.

'He was great to own and we are delighted to have had him and we shall miss him dearly.'

Ms Burton believes that the elderly gelding's personality and the fact that his previous owners did not overwork him helped him to live for so long.

Shayne had a few grey hairs and mild arthritis, despite his advanced years

She said: 'He was such a lovely horse with a great character and he showed how good a horse of this age could look.'

Shayne had a few grey hairs around his eyes and in his mane but a high-calorie diet kept him strong and he enjoyed four meals a day.

His diet included sugar beet and chaff mixed together along with alfalfa nuts, with along cabbage for treats.

Shayne, who stood at 15 hands and weighed 480kg, was put to sleep after he collapsed on February 22.

Staff at the Row Green Equine and Pet Crematorium in Braintree carried out Shayne's cremation for free, waiving their usual fee of £600.

Ella Martin, from Row Green, said: 'It was an honour to be asked to collect Shayne.

'We have worked with Remus Horse Sanctuary for many years and as a token to Sue and her team we offered to cremate him free of charge, a fitting tribute.'

The Remus team, which relies on donations to support its work, is now deciding on a final resting place for the ornate wooden cask carrying Shayne's ashes.

Last year, when the tale of Shayne's incredible longevity came to light, Ms Burton said: 'We get people who rescue a horse and they tell us that it is in its 30s so it knocks them for six when we say we have one in its 50s.'

The previous title of oldest living horse in the world was held by Welsh/Arab steed Badger, from Pembrokeshire, Wales, who died aged 51, in in 2004.

Last year, the Guinness World Records team said nobody had laid claim to the title since Badger's death.

Staff at the sanctuary believed him to be 51 based on the date of birth given by his previous owner, and medical checks.

Veterinary staff try to find out how old a horse is by looking at the condition of a horse's teeth.

How long teeth are, how worn they are, and how deep any grooves are, can all give clues as to which birthday should be celebrated.

THE OLDEST HORSE ON RECORD Old Billy, a working barge horse, was 62 years old when he died on November 27 1822. He was born in Woolston, Lancashire in 1760 and spent his life pulling barges along canals. From paintings, Billy is shown to have a brown coat with white blaze and to be similar in size to a shire horse. His skull is on display in the Manchester Museum and his taxidermied head is on display in the Bedford Museum. Advertisement

A British Horse Society spokesman estimated that Shayne's years made him the human equivalent of more than 100, but said that 'the older they get, the harder it is to tell' once horses get past their average life expectancy of early thirties.

On average, every horse year beyond the age of four is roughly the same as 2.5 human years.

Using this method, Shayne would easily be receiving birthday cards from the Queen if he were human - at a whopping 120.

As Shayne's birth was believed to be before horse passports were introduced, there would only be paperwork detailing the exact date if he were a purebreed.

But elderly Shayne fell a little way short of laying claim to being the oldest horse in history.

That title belongs to 'Old Billy' who was foaled in Woolston, Lancashire and had reached the age of 62 when he died in 1822.