Quick action by several backstretch personnel at Bowie Race Course prevented serious damage to horses and property early yesterday morning when a fire, believed to be deliberately set, broke out in the stable of trainer Richard Dutrow.

Forty 40 horses were turned loose after the fire was discovered at 12:16 a.m. Fire companies responded from Bowie, West Lanham, Anne Arundel County, Landover Hills and Greenbelt. The fire caused an estimated $14,000 in damages.

Bowie General Manager Al Karwacki said track security personnel and Prince George's County fire marshals are investigating the fire. He said the fire "was suspicious because it was started in three different places."

Fire department spokesman James Munge said a $500 reward is offered for information leading to the arrest of whoever set the fire in the barn.

Trainer Gerald Rockey was singled out by Karwacki as being primarily responsible for saving the Dutrow horses. Rockey trains horses stabled across from the Dutrow barn.

Dutrow, America's leading trainer in 1975 with 352 victories, accounted for all his horses, several of which were suffering from smoke inhalation. He scratched three horses from yesterday's card as a precaution. Dutrow was one of several trainers who lost horses in a fire at Bowie in 1966 that killed 41 horses.

An off-track betting bill that has been languishing in the Maryland House of Delegates for several weeks will be brought to the floor of the House next week. The bill, introduced by Del. Louis P. Mossberger (D-Baltimore Co.), would have OTB collecting 6 percent of the straight, place and show, with the track in operation getting 3 percent and the horsemen's purses 4 percent.

The exactas would be divided this way: OTB 8 percent; the tracks 4 percent, and the horsemen's purses 5 percent. The triples would be shared in this manner: OTB 10 percent; the tracks 6 percent, and the horsemen's purses 7 percent.