What Causes Grass Tetany?

Grass tetany, also called lactation tetany, grass staggers and hypomagnesemia, is a serious metabolic disorder that mainly occurs in milk cows, although all cattle are susceptible. The condition leads to death if it remains untreated.

Features

A deficiency of magnesium in the blood causes grass tetany in cattle. The condition usually occurs when cattle graze outdoors during the fall and spring. Cows that browse on young ryegrass, oats or wheat in December and January are at high risk of developing this disorder. Fields that have little magnesium or excessive amounts of potassium in the soil can also cause grass tetany in livestock.

Effects

Cows with grass tetany become nervous, excited or unusually alert. Their muscles twitch, and they may stumble, stagger or fall. Eventually they experience muscle contractions, breathing difficulties and seizures, followed by death. The University of Florida IFAS Extension recommends that the owner call a veterinarian immediately if he suspects grass tetany, since the disease can run its fatal course in six to 10 hours.

Prevention/Solution

Livestock owners prevent grass tetany by adding magnesium-containing dolomitic limestone to the soil to increase the magnesium levels, or by dusting fields with magnesium oxide. They also place supplemental mineral feeders in the pasture. Veterinarians treat existing grass tetany by injecting affected cattle with magnesium sulfate.

References

• University of Florida IFAS Extension: Grass Tetany
• New Mexico State University Cooperative Extension Service: Controlling Grass Tetany in Livestock