Brentwood, UK - The world's oldest horse has held its title for well over two hundred years, yet there is one horse who's coming for that title. What is the world's oldest horse right now, and why is it so old?

Horses live far longer than most people think, often exceeding even 30 years of age, growing to enormous sizes, and achieving many impressive things throughout their lives and careers.

Is it so common, though, that a stallion gets so remarkably old that it could compete with Old Billy?

So, who currently holds the animal world record for the oldest horse in the world? What horse is older than all the rest, and how does it compare to the oldest horse ever? What breeds of horses are longer living than the others?

While it hasn't been confirmed by Guinness World Records, Remus Memorial Horse Sanctuary and a number of other sources, including the Daily Mail and The Horse, suggest that the most recent contender for the world's oldest horse was Shayne, who lived in Brentwood, Essex.

A beautiful chestnut gelding, Shayne lived to be 51 years old until he passed away in 2013, having reached more than 120 in human years. There is currently no world record holder for the oldest horse alive today. As such, Shayne is the most recent holder of this record, though it was never confirmed by a particular authority.

In response to his sad passing, Shayne's owner, Sue Burton, paid tribute to him, saying that he 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."

After retiring from service, Shayne lived at the Remus Memorial Horse Sanctuary from April 2007 until his death, spending many happy years eating his fill of tasty food and lightly trotting around doing his own thing. While he spent most of his life in good health, he did suffer from mild arthritis.

"He was such a lovely horse with a great character," said Sue Burton. "And he showed how good a horse of this age could look."

The oldest horse to ever live was, as declared by Guinness World Records, a Welsh cob shire horse mix called Old Billy. Born in 1760 and passing away in 1822, Old Billy lived until he was 62 years of age. He was a cold-blooded horse with a brown coat and a generous blaze.

Bred by Edward Robinson and living most of his life in Woolston, a village in Lancashire, Old Billy served as a tow horse for most of his 62 years. In fact, this giant and gorgeous creature was used to pull ships upriver, working in the role for nearly 50 years.

Of course, such horses are very rare and unnecessary nowadays. We imagine, though, that Old Billy was probably quite a catch in his day, giving his owners plenty of years without the need to breed a replacement. No other horse has likely given its owner this much value in all the years of horse history.

It's truly extraordinary that he lived for so long, though, seeing that most horses live less than half that length of time and cold-blooded horses generally live shorter than warm-blooded horses.

Most horses live between 20 and 35 years, with the longest-living horse breed being the Arabic or the Icelandic, depending on who you ask. The temperature of a horse's blood also has a lot to do with its life expectancy, with cold-blooded horses only generally living until they are 16–18 years of age.

In comparison, warm-bloods live 20–25 years and are not considered "fully grown" until they are about five years old. Similar to how small dogs generally live longer than big dogs, the smallest horse breeds usually live the longest, with the Shetlands and other ponies being up there with some of the most fascinating and oldest horses - often living for between 25–30 years.

Ultimately, your choice of horse when adopting shouldn't be based on life expectancy but, instead, on use. Are you competing with the horse, or are you going to use it for manual labor? Choose your horse breed based on what would be best for the job at hand.