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Warfarin: An Auspicious Student Project Rebecca J. Anderson, PhD
On a frigid Saturday morning in February 1933, Ed Carlson hoisted a dead cow into his pickup truck—the latest in a series of cattle losses on his farm that winter. In December, two of his young heifers had died. In January, his favorite old cow had developed a massive hematoma on the thigh. When it was lanced, the bleeding proved fatal. Then, on a Friday in February, two more cows died, and Carlson’s bull was oozing blood from its nose (1, 2). To the local veterinarian in Deer Park, Wisconsin, the problem was all too familiar. He told Carlson there was a hemorrhagic toxin in his hay. Carlson doubted that explanation. He had been feeding the same sweet clover hay to his cattle for years with no ill effects. He decided to get another opinion—from state experts (1-3). So, on that Saturday in February, Carlson drove 190 miles through a blizzard to the Agricultural Experiment Station in the state capital. Unfortunately, when he arrived, the State Veterinarian’s office was closed (1, 2). But in the Biochemistry Building of the University of Wisconsin, Karl Paul Link and his student assistant,
The Pharmacologist • December 2019
Eugen Wilhelm Schoeffel, were still at work. Carlson hauled in the dead cow, along with a milk can of unclotted blood and about 100 pounds of hay (1-3). Link listened intently as Carlson related his sad saga. Although Link was not a veterinarian, he recognized the symptoms. They fit “perfectly with the classical sweet clover poisoning picture” (2).
Sweet Clover Turns Sour Link first heard about sweet clover disease just two months before Carlson’s arrival. Ross Gortner, the chairman of biochemistry at the University of Minnesota, had invited Link for an interview (2). Gortner gave him publications by the original researchers of sweet clover disease, which was also a problem in Minnesota. He invited Link to join the lab’s efforts to identify the substance in the hay that was causing the bleeding. This hemorrhagic disease was first characterized in the 1920s by two veterinarians, Lee M. Roderick in North Dakota and Frank W. Schofield in Alberta,