Dr. Alex Harthill, perhaps the most famous equine veterinarian in the world and one of the most legendary and controversial figures in American racing history, died early Saturday in his hometown of Louisville, Ky., from complications of a stroke. He was 80.\n"Doc" Harthill, as he was known to racetrackers everywhere, died at 6:05 a.m. Eastern at Hospice and Palliative Care in downtown Louisville. He had suffered a major stroke several weeks ago and was stricken with pneumonia at the time of his death, according to a family friend, Skip Fischer.\nHarthill had a role in innumerable major racing events, including the infamous disqualification of the 1968 Kentucky Derby first-place finisher, Dancer's Image, for whom Harthill served as the attending veterinarian. By his own count, he treated at least 26 Derby winners, from Citation to Northern Dancer to Sunday Silence.\nA tireless worker who had no hobbies besides his work with racehorses, Harthill made hundreds of friends in the racing industry, most notably jockey Bill Shoemaker and trainer Charlie Whittingham, both of whom preceded him in death. His offices at The Harthill Co., the successful veterinary-supply company that was headquartered just outside the stable gate of Churchill Downs, were packed with photos and memorabilia from his nearly six decades in racing.\nFischer said Saturday afternoon that news of Harthill's death had spread quickly and the family had been fielding phone calls "from all over the world."\nBorn April 30, 1925, in Louisville at his father's veterinary hospital, where the family had an apartment, Alex Harthill always intended to follow in his father's footsteps. He wasted little time in doing so, graduating from veterinary school at Ohio State University in 1948 and immediately beginning a racetrack practice.\nIn the ensuing years, Harthill became widely known as a world-class veterinarian. In a 2002 article in Daily Racing Form, his longtime colleague Dr. Jock Jocoy of California said: "In my opinion - and I think I have a right to one - Alex Harthill was one of the best at all the things a vet needs to know. He could diagnose, treat, suture - he had perfect feel for all the mechanics of the work."\nJoe Hirsch, the retired executive columnist for DRF, was friends with Harthill for more than 50 years. "Dr. Harthill was an outstanding individual and an outstanding veterinarian," said Hirsch. "He had an intuitive sense about what was bothering a horse. He went far beyond conventional means to determine what was ailing them. He was very, very talented. He also was extremely generous with his time, especially with horsemen who might not have been able to afford his services. He will be sorely missed."\nAlthough his legacy as a practicing veterinarian was sealed early, Harthill quickly became synonymous with controversy and seemed to live on the edge of racing legality. Intense speculation long has swirled about his role in the disqualification of Dancer's Image, who tested positive for Butazolidin, an anti-inflammatory drug that was banned at the time. He was arrested in the 1950's in Louisiana for allegedly bribing a testing laboratory employee. He was persona non-grata in recent years in New York, and he was a central figure in countless racetrack controversies and court cases in Kentucky and elsewhere.\n \nHarthill's roles in high-drama racing events were equally compelling. He was part of the surgical team that tried unsuccessfully to salvage the life of Ruffian after the filly broke down in her match race with Foolish Pleasure at Belmont Park in July 1975. He treated a lame Sunday Silence in the week leading to the 1989 Preakness, which the colt ultimately won in a sensational duel with Easy Goer. He attended to A.P. Indy on the morning of the 1992 Derby, when a disappointed Neil Drysdale announced the colt had to be scratched because of lameness.\nDespite his hectic schedule - Harthill was famous for getting by on amazingly little sleep - he frequently served on racing boards, and in the early 1980's he even served as director of racing at Fair Grounds in New Orleans. More recently, he served for several years as president of the Kentucky division of the Horsemen's Benevolent and Protective Association. Over the last decade or so, he was honored on several occasions for lifetime service by racing groups and associations, including the Shoemaker Found-ation in 2001.\nHarthill was extremely vocal in his support of liberal medication rules and often said that the appropriate use of drugs for raceday purposes "only help the horse." He even admitted skirting the rules in enabling horses toward that end. In DRF articles in recent years, he said he administered Lasix, which was banned at the time, to Northern Dancer before the colt won the 1964 Derby, and he admitted to regularly using the bronchodilator clenbuterol some 20 years before it was approved by the Federal Drug Administration in May 1998.\nNonetheless, when asked technical questions about drugs in racing, he would back off. "I'm not a chemist," he would say, "just an old horse doctor."\nHarthill had an engaging smile, a sly sense of humor, and a soft side, but he also was known for a quick temper. He rarely shied from confrontation and frequently spoke of challenging men to fight. In a 1998 interview, he fondly recalled his rough-and-tumble younger days, when he was a close friend of Warner Jones, the late Churchill Downs chairman. "We'd go out to Warner's place on Sunday afternoons, way before there was Sunday racing," said Harthill. "We'd drink whiskey and have bare-knuckle fistfights, just for the fun of it."\nHarthill married three times; he was widowed once and divorced twice. He is survived by two daughters, Meha Harthill of Irvine, Calif., and Alexis Borden of Louisville.\nFuneral services are being handled by the Heady-Cralle Funeral home on Frankfort Ave. in Louisville. Visiting hours will be held Wednesday from 5-8 p.m. Eastern, with a memorial service to follow. The body will be cremated, and some of his ashes will be flown overseas to be spread in the family's ancestral home of Harthill, Scotland.\nMemorial contributions can be made to the Shoemaker Foundation, the Kentucky chapter of the Racetrack Chaplaincy of America, or Hospice and Palliative Care of Louisville.