Please help to stop the horse carriages in Merida/Yucatan/Mexico

Something should be done for the horses in Merida in Mexico.
I have been in Merida quite a few times and seen the horses working in the center of the town as horse carriage, taking the tourists on a trip around town.
They look terrible and thin, I've never seen them being fed or had water, they work hard, long days and when not on their round trip, they stand in line in the heat and burning sun without a shed.

Please help making this terrible abuse come to an end!