The slaying of more than 20 pet horses in Florida for meat has prompted a bill being filed in the state legislature.

Florida Representative Luis Garcia (D-Miami) and Florida Senator Victor Crist (R-Tampa) have filed identical bills that would make horse slaughter illegal in the state.

The slaughter of horses for meat, centred around Miami-Dade County, has horrified horse owners across the state.

Authorities investigating the killings say the meat is likely being used to fulfill a strong illegal demand. Horse meat can reportedly fetch up to $US20 a pound.

The bills make it illegal to "knowingly transport, distribute, sell, purchase, or possess horsemeat for human consumption that is not clearly stamped, marked, and described as horsemeat for human consumption or horsemeat that is not acquired from a licensed slaughterhouse".

Campaigner Richard Kouto has highlighted the plight of the animals and points to a string of illegal slaughterhouses operating in an area known as the C-9 basin.

The market is likely fuelled by the high proportion of Miami-Dade residents of Cuban orgin. Horse meat is commonly eaten in Cuba.