The remains of the latest horse were found in southwest Miami-Dade County, which has been centre of most of the killings.
Several bodies have also been found in neighbouring Broward County.
The animal was left beside a dirt road in the Redland area, its remains sitting on an old door and covered in garden debris.
Authorities believe the horses are being slaughtered as part of a trade in illegal horse meat, which can fetch up to $US20 a pound.
While five people have been charged as a result of police inquiries, detectives have warned that the arrests most likely related to isolated incidents, indicating that the wider problem still remains.
The latest case comes just days after a multi-agency team blitzed an area known as the C-9 Basin, in Miami-Dade's rural western reaches.
It has long been the home to illegal slaughterhouses, suspected of being behind the illegal trade in horse meat.
While no stores of illegal horse meat were found, multiple violations of business, health and environmental regulations were found and at least one unlicensed slaughterhouse was located and shut down.
The identity of the latest horse has yet to be established and may prove difficult. Not only has the meat been removed, but the animal is missing its head and legs, and was skinned.
It is against the law to sell horse meat in the US.