Grass tetany (hypomagnesaemia) kills cattle rapidly and often without warning, particularly in spring-grazing cows. Understanding risk factors and implementing prevention saves lives and prevents suffering.
Grass tetany causes acute, severe neurological suffering - convulsions, muscle spasms, and respiratory distress that develop rapidly and are terrifying to observe. The welfare tragedy of grass tetany is its near-complete preventability through appropriate supplementation. Farmers who have experienced losses know the pattern: a previously healthy cow found dead or in convulsions in the spring. Prevention requires anticipating the risk period and implementing supplementation before clinical signs appear - once a cow shows symptoms, the opportunity for comfortable prevention has passed and emergency treatment becomes the only welfare option. The speed of progression means that waiting to see if supplementation is needed is not a welfare-acceptable approach during known high-risk periods. Systematic supplementation programs have dramatically reduced grass tetany deaths where adopted.