Causes, prevention and treatment of the disease seen primarily in spring
Spring brings a host of wonderful things for farmers; green grass, warmer weather and baby animals just to name a few. But the early months of spring also usher in a potential problem – grass tetany. Without prevention or treatment, grass tetany can develop into a life-threatening disease.
Grass Tetany Causes
Grass tetany has other names such as winter tetany and magnesium deficiency. Grass tetany emerges as a potential problem when cool season forages start to grow in pastures where animals graze. The disease typically occurs in the Ozarks during the months of February, March and April.
Grass tetany is due to an abnormally low level of magnesium in a cow’s body. “Ruminant animals absorb magnesium from the intestinal tract much less efficiently compared to other grazing species,” Dr. Jeremy Powell, DVM, Ph.D., a professor and veterinarian at the University of Arkansas Division of Agriculture, explained.
Magnesium levels can also drop due to losses in the milk of a lactating cow. Additionally, low magnesium levels can be attributed to an increase in a cow’s potassium intake. “High potassium levels occur in young, rapidly growing forage and can be a problem in cool season grasses such as fescue or in winter annual cereal grains like wheat, rye and oats,” Powell said. “High potassium levels directly interfere with the cow’s digestive ability to absorb adequate magnesium.”
There are several other factors that may impact the disease. For example, cloudy and/or misty weather affects plants availability of magnesium. If producers use pot ash (potassium) to fertilize a pasture where animals are grazing, that can also limit magnesium uptake.
In addition, things that can be stressful to animals such as hauling, penning, calving, cold weather or heavy lactation can all increase the likelihood of an animal getting grass tetany. Most commonly, the illness occurs in older, lactating cows. Grass tetany can affect cattle as well as small ruminants like sheep and goats.
Prevention
The best defense against grass tetany is prevention. “This can be achieved by providing a mineral supplement containing at least 10 percent magnesium (“high mag mineral”). Cattle should consume 2 to 4 ounces of mineral supplement each day,” Powell recommended.
Producers should make sure animals have access to the supplement daily because a cow’s body doesn’t possess the ability to store up reserves of magnesium. Powell suggests producers make several mineral feeders available if stocking rates are higher for the herd.
According to Powell, younger non-lactating animals seem to be less likely to have issues with the disease; therefore, grazing young animals on high-risk pastures can be another method of prevention.
Signs of the Disease
Producers will want to keep an eye out for signs of grass tetany. The early signs of the disease are subtle. The first symptoms include decreased appetite, decreased milk production, frequent urination, separation from the herd, hypersalivation (slobbering), increased excitability as well as a stiff or unsteady gait.
It’s important to monitor cattle closely because the first signs of grass tetany may occur for as little as two to three hours which makes early detection difficult. “As the disease progresses, an affected cow will lose normal muscle control and usually exhibit muscle tremors and spasms. The affected animal will eventually lie down, and they become unable to get up,” Powell said.
If the disease is left untreated, it can lead to death. Due to the fast progression of the disease, if producers cannot check their cattle on a regular basis, then the first sign of a problem may be a dead cow.
Treatment of the Disease
Experts recommend producers work with their herd veterinarian on the appropriate treatment options. “Successful treatment of the disease will focus on correcting the magnesium imbalance, and this can typically be accomplished by administering intravenous electrolyte solution (CMPK). This treatment is not without risk, and it is important to administer this solution slowly while monitoring heart and respiratory rates closely,” Powell advised.
Local extension offices and university extension websites offer additional information and factsheets on grass tetany and other livestock diseases.
For more information about cattle diseases, contact your county Extension office or by accessing this factsheet provided by University of Arkansas Cooperative Extension: uaex.uada.edu/publications/pdf/FSA-3084.pdf
