As spring pastures begin to green up, producers should be aware of the risk of grass tetany, also known as “grass staggers.” While most commonly associated with cattle, this condition can also affect sheep and goats and may result in serious losses if not recognized and managed promptly.

What is Grass Tetany?
Grass tetany is caused by low levels of magnesium in the blood. Magnesium is essential for proper muscle and nerve function, and unlike some nutrients, it is not stored in large amounts in the body. Animals must consume adequate magnesium daily through their diet. This deficiency most commonly occur when forage is naturally low in magnesium, such as during spring green up!

Grass tetany is most often seen during periods of rapid forage growth, particularly in early spring. Lush, immature grasses tend to be:

• Lower in magnesium
• Higher in nitrogen and potassium, which can reduce magnesium absorption
• High in water content, which dilutes nutrient concentration

Additional risk factors include:

• Heavy nitrogen or potassium fertilization
• Cool, cloudy weather
• Pastures dominated by cool-season grasses such as ryegrass
• Animals with higher nutrient demands, including those in a lactation period

Symptoms
In many cases, the first sign may be a sudden death in the pasture. However, early symptoms can include:

• Nervous or excitable behavior
• Animals separating from the herd or flock
• A “wild” or alert stare with ears up
• Muscle twitching or tremors
• Stiffness, incoordination, or staggering

As the condition progresses, animals may collapse, experience seizures, fall into a coma, and die.

Treatment
Grass tetany is a medical emergency. Treatment is only effective in the early stages—often within one to two hours of observing symptoms. Administration of magnesium (typically by injection) is the standard treatment.

Prevention
Prevention is the most effective approach to managing grass tetany. Recommended practices include:

• Delay turnout on pasture until forage is at least 4–6 inches tall
• Avoid turning out hungry animals; provide hay prior to grazing
• Supplement magnesium daily, especially during high-risk periods
  • Provide a high-magnesium mineral free-choice at all times
• Incorporate legumes such as clover into pastures to improve magnesium intake
• Manage soil fertility carefully, avoiding excessive nitrogen and potassium applications
• Use lower-risk animals (e.g., dry cows, stockers, heifers) on high-risk pastures
• Provide supplemental forage like hay to balance intake

Lush spring forage does not always provide balanced nutrition. Monitoring pasture conditions, animal behavior, and mineral supplementation is essential to reducing risk. Because grass tetany can progress rapidly and often without warning, proactive management is far more effective than treatment.

For additional guidance on mineral supplementation, pasture management, or livestock nutrition, contact Sarah Newman, the Cabarrus Livestock and Field Crops Agent at 704-920-3310 or sarah_newman@ncsu.edu.