Grass Tetany in Livestock

Grass tetany can be a serious and even fatal problem for different types of livestock. Understanding and recognizing the condition, however, can help you keep your animals healthy and prevent grass tetany from taking a toll on your livestock.

About Grass Tetany

Grass tetany is a magnesium deficiency in an animal’s blood and is often more common in lactating females or older animals that have more difficulty absorbing magnesium. Ruminants are susceptible to grass tetany, including cattle, sheep, and goats, and the disease is most common in spring and fall when pasture may not have as much new growth rich in magnesium. The disease is also known as grass staggers, wheat pasture poisoning, magnesium tetany, milk tetany, or hypomagnesia.

Several different factors can cause grass tetany. Any diet low in magnesium can lead to the condition, and high levels of milk production also make an animal more susceptible to grass tetany. Poor magnesium metabolism can also be caused by a diet that is too high in nitrogen or potassium, both of which block magnesium absorption.

Grass Tetany Symptoms

It can be difficult to diagnose grass tetany in livestock because symptoms are generally mild until the animal is so badly affected that death occurs. Depending on the severity of the magnesium deficiency, however, the following symptoms may be noticeable while there is still time for treatment:

• Excitable or nervous behavior
• Wild staring or unusually focused gaze
• Grazing away from the herd
• Stumbling, twitching, or generally uncoordinated movement
• Frothing at the mouth
• Convulsions
• Coma
• Collapse

An infected animal can die within hours of symptoms first appearing, making it vital that grass tetany be treated immediately.

Treatment Options

Because symptoms may not be noticed right away once an animal begins to exhibit signs of grass tetany, treatment can be difficult. Administering a magnesium supplement is essential, and can be done in several ways. Oral magnesium may be used if symptoms are mild and the animal is in otherwise good health, but it may not be absorbed quickly enough to save the animal’s life. An intravenous solution of magnesium and calcium can be more effective, or a subcutaneous injection of magnesium sulfate is another option for severe cases. Regardless of the choice, a veterinarian should be contacted right away for this type of health emergency, and if one animal shows symptoms of grass tetany, all animals in the same herd or pasture should be closely monitored to catch additional cases right away.

Preventing Grass Tetany

Because grass tetany can strike so quickly and fatality can be high, it is better to take preventative steps to protect vulnerable livestock rather than rely on noticing symptoms and administering treatments case-by-case. Several options are available to prevent grass tetany in livestock, including:

• Choosing pastures with legume grasses, including clover and alfalfa, that are naturally higher in magnesium. As the animals graze, they are more likely to ingest adequate magnesium.
• Avoiding grazing on very new or young grasses. Fresh growth has less magnesium in its foliage and will not be an adequate magnesium source in an animal’s diet.
• Avoid nitrogen fertilizers on pasture grasses, particularly in spring when livestock is most susceptible to grass tetany. Excess nitrogen inhibits magnesium absorption.
• Provide a magnesium supplement to vulnerable livestock. Consult a veterinarian for the proper supplement and dosage, but be aware that magnesium is not stored in the body so the supplement must be a daily dietary addition to be most effective.

No matter whether it is called wheat pasture poisoning, grass staggers, or hypomagnesia, grass tetany in livestock can be a devastating condition. By recognizing this condition and understanding where it comes from, you can easily take preventative steps to protect your animals and ensure they have appropriate levels of magnesium as part of a healthy, nutritious diet.