The move follows the deaths of 21 international-class polo ponies in Florida in April after they were injected with a mixed supplement containing an incorrect quantity of selenium.
The testing programme will begin in January, coinciding with the start of the polo season.
Testing will be mandatory for any horse selected.
The decision was made by the United States Polo Association, which set up a committee following the Florida tragedy to explore ways of improving polo pony safety.
Federal and state inquiries are continuing into the circumstances leading to the deaths of the horses, all members of the Venezuelan-owned Lechuza Caracas team.
They began to collapse on April 19 at the International Polo Club Palm Beach, in Wellington, as they were being unloaded for a match.
Intensive veterinary care was unable to save the animals.
Polo officials spent time reviewing drug-testing regimes in other horse-related sports, including the Hurlingham Polo Association, which oversees polo in the UK and Ireland. It has drug testing for horses and players.