Scores of horses are being cared for following a massive rescue operation after animals were "left to die".
They were found in a field with more than 30 other dead animals, the RSPCA said. It found 31 dead horses, ponies and donkeys when it was called to the site in Amersham, Buckinghamshire, over the weekend.
Animal welfare workers removed 14 animals immediately and three more were in such a poor condition they had to be put to sleep on veterinary advice.
On Tuesday an operation to remove the 84 surviving horses took place. The RSPCA said later that all the horses had been removed and were being cared for. Neighbours said that they believed the animals to be part of the stock belonging to a local horse trader.
The horses were being taken to sanctuaries by the RSPCA, Redwings Horse Sanctuary and the International League for the Protection of Horses.
A spokeswoman for Redwings Horse Sanctuary said: "Redwings Horse Sanctuary has travelled to rescues on many occasions but rarely sees cruelty so far advanced that equines are seemingly forgotten and literally left to die."
The British Horse Society's Welfare Senior Executive Lee Hackett said: "Mistreatment on this scale is unprecedented in Britain - the true horror of the situation is only now becoming clear."
The Horse Trust is looking after many of the worst affected animals at The Home of Rest for Horses sanctuary in Speen, Berkshire.
Over the weekend they took in 10 young colts and geldings and one blind dun mare. They are also caring for three donkeys including a six-month-old foal. Another 17 animals, said to be in a less serious condition, arrived yesterday.
Thames Valley Police said a man arrested on separate police charges would appear before Aylesbury magistrates on Monday. James Gray, 44, from Amersham, was charged with criminal damage and assault on a police officer and released on bail, a spokesman said. Police would not confirm Gray's connection with the operation.
