Police on patrol in Los Robles in the canton of Los Chiles came upon three men driving horses into Costa Rica from Nicaragua.
Police said that the horses were in deplorable condition and some were close to death.
Two of the men who were mounted fled, but a third was detained, said police. The location is just a kilometer from the border.
Police also encountered a man in a truck a short distance away, but the man denied all knowledge of the horses, police said.
Police said the animals were malnourished and covered with ticks. Some were lame and some even were blind.
Although police confiscated the animals in conjunction with the Servicio Nacional de Salud Animal, many probably will
have to be put down after being inspected.
Police did not say why the animals were being brought into Costa Rica, but a possibility would be to be slaughtered and processed.