Merck Manual

Please confirm that you are a health care professional

honeypot link

Disorders of Calcium Metabolism in Horses


Sharon J. Spier

, DVM, PhD, DACVIM, Professor Emeritus, University of California, Davis

Last full review/revision Oct 2019 | Content last modified Oct 2020

Hypocalcemic tetany in horses is uncommon but can develop after prolonged physical exercise, such as endurance rides, or transport (transport tetany) and in lactating or nursing mares (lactation tetany). A low level of calcium in the blood (hypocalcemia) can be caused by decreased absorption from the intestines, by increased loss through the milk, urine, or sweat, or by changes in bone metabolism. Producing large amounts of milk and grazing lush pastures make lactating mares more inclined to develop the condition.

Signs correspond to the level of the active form of calcium in the blood, and most relate to muscular spasms, tremors, and stiffness. Other signs include inability to chew, spasm of the jaw muscles, drooling, lying down, seizures, and irregular heart rhythms. In severe cases, synchronous diaphragmatic flutter Synchronous Diaphragmatic Flutter Muscle cramping is a painful condition that arises from hyperactivity of motor units caused by repetitive firing of the peripheral and/or central nervous system. The origin of the cramp in most... read more may develop. In this condition, the diaphragm contracts at the same time as the heart to produce loud thumping noises (heard with a stethoscope) and usually visible contractions in the flank area.

Calcium solutions given intravenously usually result in full recovery. Some horses need repeated treatments over several days. Throughout pregnancy, mares should be fed a balanced ration that contains adequate amounts of calcium and phosphorus in the correct ratio. When calcium demands are increased, when nursing a foal, mares should be fed high-quality forage such as alfalfa or calcium-containing mineral mixes. Stress and fasting during transport should be minimized.

For More Information

Others also read
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Test your knowledge
Neoplasia of the Eye and Associated Structures
Squamous cell carcinoma is a common neoplasm in several species. Ocular squamous cell carcinoma is most common in animals with light pigmentation around the eyes, because sun exposure is one of several predisposing factors. This tumor is common in each of the following species EXCEPT:
Become a Pro at using our website 

Also of Interest

Become a Pro at using our website