Trainer King T. Leatherbury, twice a national champion for number of races won, was handed a 15-day suspension yesterday by Timonium stewards after one of his horses tested positive for phenylbutazone, a pain killer.

The suspension, which begins Thursday, is the first of Leatherbury's 23-year career. After a Monday hearing, he requested an appeal and stay, which was rejected by the Maryland Racing Commission.

"This whole thing is devastating to me," Leatherbury said.

It could not be determined whether Leatherbury will exercise his option of seeking a court injunction. He could not be reached for comment yesterday.

Leatherbury, currently the leading trainer at Timonium, trains the 3-year-old gelding War On The Rise, who finished second in a race on July 29. Officials said postrace testing showed that the horse's system contained a greater level of phenylbutazone, commonly called Bute, than Maryland racing rules allow.

Horses are not permitted to receive Bute once they have been entered in a race, usually 48 to 72 hours before post time.

At Monday's hearing, Leatherbury said his horse's level of Bute was well over the maximum allowed (two micrograms per milliliter of blood).

"As far as I know, once the horse was entered he should not have received Bute," Leatherbury said. "I don't know how the horse got it. I don't know if it was some sort of sabotage or not."