An abandoned pony found to have five feet is undergoing veterinary treatment for the rare condition at the Horse Rescue Fund in Norfolk.
The 13hh piebald stallion was rescued from an isolated area of land between a railway and a river last November.
The Environment Agency asked the Horse Rescue Fund to take in the pony after the owners failed to respond to a removal notice.
The pony was found to be not the yearling colt the Horse Rescue Fund had been asked to collect, but an eight-year-old stallion.
He was named Trooper as the rescue took place the week before Remembrance Sunday.
The stallion was found to be in good condition apart from his feet, especially his off fore.
Staff at the Horse Rescue Fund were shocked to discover on removal of his feathers, Trooper had an extra hoof.
Following clinical examinations and X-rays by Wherry Vets in Bungay and Rossdales in Newmarket it was discovered that Trooper had a duplicate lower limb growing just below the knee.
The extra leg protruding from the off fore had a normal cannon bone followed by an undeveloped pastern, pedal bone and hoof.
“Where the extra digit had been allowed to grow and strike the ground repeatedly the pressure had created a large split in the skin which had become infected with maggots,” explains Sue Albone from the charity.
“The farriers first job was to carefully reduce the extra hoof in length by 4cm, avoiding the sensitive tissues within, thus reducing the risk of injury to his other leg,” said Albone.
“His main hoof, should, in time, improve with regular trimming.”
The rare condition is known as a polydactyl or polydactylism, the term meaning extra digits.
The first case of polydactylism recorded in horses was in the early 1990s in a shire horse called Norfolk Spider.
The famous horse was nicknamed the “Six Footed Shire”.
The extra digit can be removed but Trooper is not going to have an operation as he seems to be managing well with ongoing veterinary treatment.
“Currently he is adjusting to life on the yard with the other rescue equines and is a firm favourite with staff due to his placid and sweet nature,” said Sue Albone.
The charity hopes to find a suitable companion home for the pony after his rehabilitation.