Rescuers are attempting to save more than 80 neglected horses that were found in a field in Buckinghamshire with lots of dead animals.
Police officers and animal sanctuary staff were helping with the rescue effort in Amersham.
Animal charity the RSPCA found 31 dead horses, ponies and donkeys at the site when they were called at the weekend.
A 44-year-old man has been arrested on suspicion of assaulting a police officer and criminal damage.
The animals had been neglected and left where their bodies had fallen, animal welfare workers said.
Fourteen animals were removed immediately and three others were so poorly that they had to be put to sleep.
The remaining 84 horses are now being removed and taken to sanctuaries.
It's not yet been revealed who was meant to be caring for the creatures, but an RSPCA spokesman said the charity was likely to be taking them to court.