Up to 15 federal, state and county agencies were involved in the operation on Tuesday.
Authorities were seeking evidence in the area known as the C-91 basin of illegal slaughter farms, where campaigner Richard Couto says hundreds of horses have met a cruel and barbaric fate.
Horse meat is popular among residents of Cuban origin and the butchering of pet horses in the last year for their meat has grabbed international headlines.
Last year alone, at least 22 pet horses were slaughtered, their remains often dumped on a roadside.
Local media report at least 100 police officers and other officials involved in the operation, including environmental and food safety inspectors.
The operation, reportedly planned for months, was aimed at closing down unlicensed slaughterhouses that operate openly in the area.
While Couto says horse meat is the most profitable for the backyard butchers, the officials were also seeking evidence of the illegal slaughter of other animals such as pigs, goats and chickens.
Miami-Dade has only two licensed slaughterhouses.