A HORSE which made world veterinary history began a well-earned retirement in Lacey Green this week.

Xena, the world's first pregnant horse to be fitted with a pacemaker before giving birth, arrived at The Home of Rest for Horses, Slad Lane, on Tuesday.

The seven-year-old Irish draught/thoroughbred mare was fitted with the cigarette box-size device last year after Xena suffered a series of collapses during which her heart would stop for up to 20 seconds.

Rebecca Keating, who works at the home, said everyone was excited about Xena's arrival.

She added: "We are certainly looking forward to Xena coming to stay with us.

"She's coming here to enjoy her retirement in the beautiful setting of the Chiltern Hills."

Surgeons at The Royal Veterinary College, Hertfordshire, who put Xena under the knife, created equine medical history in carrying out the procedure.

The pacemaker was slipped under the skin of Xena's neck with a lead running through her jugular vein to her heart.

The steed was forced to have the risky operation while in foal to the showjumping champion Renkum Valentino because of a rare condition called heart block.

Xena gave birth to a foal named Viper which has now been weaned off her mum who will spend her remaining days at the home.

The Home of Rest for Horses, which is the biggest provider of funds for equine welfare in the United Kingdom, looks after 120 horses and is renowned for its interesting residents.

It is open to the public daily and is funded through donations and charity events.

Last year the home played host to an emotional reunion between a policeman and his old horse who were both injured by an IRA bomb.

Three horses from the Hyde Park barracks of the Household Cavalry, bombed by the IRA in 1982, still live at the home.

One of the horses, Echo, celebrated its 30th birthday last year and has been at the stables longer than any other horse.