why was he euthanized?
Secretariat became afflicted with laminitis—a painful and debilitating hoof condition. When his condition failed to improve after a month of treatment, he was euthanized.
Death
In the fall of 1989, Secretariat became afflicted with laminitis—a painful and debilitating hoof condition. When his condition failed to improve after a month of treatment, he was euthanized on October 4 at the age of 19. 
how many lengths did secretariat win the belmont stakes 31 lengths. who was "secretariat"? An American Thoroughbred racehorse. who owned this horse? Penny Chenery. how many years did it's career is racing last? From 1972 to 1973. which was the last race the horse competed in? Canadian International Stakes . where is this competition held? Woodbine Racetrack in Toronto, Ontario. who built this racetrack? The Ontario Jockey Club under E.P. Taylor. how did the above mentioned horse die? He was euthanized.
He became afflicted with laminitis—a painful and debilitating hoof condition. His condition failed to improve after a month of treatment, for laminitis Secretariat became afflicted with laminitis—a painful and debilitating hoof condition which failed to improve after a month of treatment.
Secretariat (horse) Secretariat (horse) Secretariat (horse)
Death Death Death
 Secretariat became afflicted with laminitis—a painful and debilitating hoof condition. Secretariat became afflicted with laminitis—a painful and debilitating hoof condition. When his condition failed to improve after a month of treatment, In the fall of 1989, Secretariat became afflicted with laminitis—a painful and debilitating hoof condition. When his condition failed to improve after a month of treatment, he was euthanized on October 4 at the age of 19.
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Secretariat (horse) [SEP] Death
In the fall of 1989, Secretariat became afflicted with laminitis—a painful and debilitating hoof condition. When his condition failed to improve after a month of treatment, he was euthanized on October 4 at the age of 19. Secretariat was buried at Claiborne Farm, given the rare honor of being buried whole (traditionally only the head, heart, and hooves of a winning race horse are buried). At the time of Secretariat's death, the veterinarian who performed the necropsy, Dr. Thomas Swerczek, head pathologist at the University of Kentucky, did not weigh Secretariat's heart, but stated, "We just stood there in stunned silence.