The latest horse is at least the 20th slaughtered this year in Miami-Dade or Broward counties in what police believe is a lucrative black-market trade in illegal meat.
The horse meat can reportedly fetch up to $US20 or more a pound.
The latest body was found on Saturday by a couple, identified as Mr and Mrs Perez, while horseback riding in Southwest Dade County.
The couple told the South Florida SPCA that they found the animal on a trail ride. They identified it as a young filly and said it was shod.
The South Florida SPCA's Richard Couto, who went to the scene, described it as a horrifying crime.
"The horse was found in multiple parts at SW 207th Ave and 195th Street.
"She's a three to four-year-old thoroughbred, you know, a baby, literally in pieces."
Couto had advice for horse owners: "If you're having barn watches in your communities, keep them going.
"If you have security lighting security cameras, if you're bolt locking your gates at night, keep doing that. The problem is not going to go away."
The SPCA said it was continuing to work with authorities to expose the criminals behind the series of killings.
Police have been probing the killings and in September arrested two men as part of their inquiries.
A man, 18, is alleged to have slaughtered one horse and was intending to carry out another killing on the evening of his arrest. A 19-year-old was also arrested as a co-defendant. Investigators said at the time that they believed one of the men was involved in the slaughtering of horses at two separate locations.
However, police warned: "Detectives advise that these cases appear to be isolated incidents.
"The ongoing investigation into other previously released horse slaughter cases remains open at this time."
Police have also made two arrests for illegally selling horse meat for human consumption. Police again advised that they considered it an isolated incident and unrelated to any prior reported case of slaughtered horses.
Miami-Dade Crime Stoppers says any informant with a tip leading to an arrest could be eligible for a reward which stands at $US15,000.
"Buying or selling horse meat is illegal in South Florida," it said.
"The illegally butchered animals were given steroids, tranquilizers, and antibiotics on a regular basis so their meat is toxic to people."