Keith Poulsen’s jaw dropped when farmers showed him images on their cellphones at the World Dairy Expo in Wisconsin in October. A livestock veterinarian at the University of Wisconsin, Poulsen had seen sick cows before, with their noses dripping and udders slack.

But the scale of the farmers’ efforts to treat the sick cows stunned him. They showed videos of systems they built to hydrate hundreds of cattle at once. In 14-hour shifts, dairy workers pumped gallons of electrolyte-rich fluids into ailing cows through metal tubes inserted into the esophagus.

“It was like watching a field hospital on an active battlefront treating hundreds of wounded soldiers,” he said.