Murli Manohar, B.V.Sc., Ph.D., of the University of Illinois College of Veterinary Medicine, estimates that as many as 70 to 80 percent of Thoroughbred racehorses are "bleeders." After exercise - often even a mild warmup (breezing) - blood Hows from their nostrils or can be seen in the bronchial tubes with special scopes. "When 80 percent of animals have a condition, usually you would consider it to be normal and wonder what was wrong with the other 20 per cent that they didn't have it;' Dr. Manohar said. Dr. Manohar is studying bleeders at the University of Illinois through a grant from Morris Animal Foundation, Englewood, Colorado. The non-profit Foundation funds studies of the health problems of horses, dogs, cats and zoo animals.