Most people don’t think of grass as poison, but dry weather and drought can turn a pasture dangerous.

Nitrates and prussic acid built to lethal levels in the stems and leaves of some plants as the hot days of July and August slowed forage growth to a halt. To protect your herd, University of Missouri Extension experts recommend a simple test to ensure cows aren’t chewing their way to disaster.

“Be aware of warm-season annual grasses, especially when fertilized with 50-60 pounds of nitrogen and coming out of very dry weather,” said Craig Roberts, an MU Extension forage crops state specialist. “Each of those factors causes the risk to go way up, and if all are present never send cattle in or feed without testing.”

Symptoms in livestock and horses can range from heavy breathing, gasping and slobbering to trouble walking, trembling, rapid pulse and death. These symptoms are similar for both nitrate and prussic acid poisoning,