One of the geldings seized from an area in South Florida
One of the horses, identified as a former thoroughbred racehorse, went into the care of Florida TRAC - Thoroughbred Retirement and Adoptive Care.
The other 10 were taken in by the South Florida SPCA.
The animals were found around noon on Sunday along Southwest 205th Avenue between 136th and 154th streets.
Efforts are under way to establish ownership of the horses.
It is possible they may have been abandoned, but Richard Couto, a high-profile campaigner against the illicit horse-slaughter trade in southern Florida, said it may also have been a pre-slaughter holding area.
He believed dozens of illegal slaughter farms were near the site, in an area notorious for its slaughter trade.
At least one of the horses had died only days before the SPCA arrived. The removed animals were described as variously underweight, old and lame.
Miami-Dade Police are investigating.