Animal welfare officers moved more than 80 neglected horses from a field in Buckinghamshire on Wednesday where the bodies of 32 others were found at the weekend.
The RSPCA said it had taken 14 horses from the field near Amersham over the weekend after being alerted by a member of the public.
Three other horses were in such poor condition they had to be destroyed, it said.
A number of the 86 rescued horses, ponies and donkeys will be cared for by the Redwings Horse Sanctuary.
A spokeswoman for the sanctuary said it was one of the largest animal rescues they had ever been involved in.
RSPCA Chief Inspector Rob Skinner told BBC television that some of the horses found dead had lain in the field for an "extended time".
It said the incident could lead to a prosecution.
Thames Valley Police said a man had been arrested on separate charges.
