The Maine State Harness Racing Commission suspended and fined seven licensed harness racing trainers for giving excessive levels of cobalt to horses.

Cobalt, which can serve as a performance-enhancing drug in horses, was banned by the Association of Racing Commissioners International two years ago. The use of cobalt is a violation of the commission’s Medication and Testing rule that aims “to protect the integrity of live harness horse racing, to guard the health of the horse, and to safeguard the interest of the public,” according to the Maine Department of Agriculture, Conservation and Forestry, which appoints the commission members.

Maine horse racing trainers Steven Vafiades, Randy Bickmore, Patricia Switzer, Stephen Murchison, Drew Campbell, Allison McDonald and Frank Hiscock were fined up to $2,250 each and required to return purse winnings, according to the department.

Cobalt improves the performance of horses by increasing the number of red blood cells, said the Maine Harness Racing veterinarian, Zach Matzkin.

Excessive uses of cobalt in horses has been proven to cause colic symptoms, muscle twitching, excessive sweating and general discomfort, according to the Racing Medication and Testing Consortium in Lexington, Kentucky.

Matzkin said the problem of cobalt in Maine harness racing has vanished since the horses trained by those seven men tested positive in 2015. No other tests have come back positive since, and the department now tests frequently, Matzkin said.

Matzkin said the tests in April 2015 were the first time cobalt was found in testing of Maine horses.

Colbalt is “a very good way to enhance performance, but tests (to see if it’s fatal) have not been done on horses. It has some very strong acute effects and clearly makes horses uncomfortable,” Matzkin said.

There are about 215 licensed horse trainers in the harness-racing industry in Maine and about 2,000 horses, Matzkin said.

“We’re constantly testing now. This has been out there for a long time,” Matzkin said.