Hypocalcaemia is an abnormally low level of blood calcium. On farms it is mostly seen in cows prior to and soon after calving. In sheep it is usually seen in ewes in late pregnancy but can be seen in all classes of animals. The disease is seen when the body fails to mobilise enough calcium from the bones to maintain normal blood calcium levels, or when certain compounds known as oxalates bind up the calcium.
Ewes in late pregnancy should not be without feed for more than 18 hours. If not watched closely this may occur in "grazed out" paddocks, transportation or holding sheep in yards. Other causes may include a sudden drop in temperature, sudden stress, feeding grain diets over a long period of time without calcium supplements, grazing green oats, wheat, or rapidly growing grasses, hard grazing of pastures composed mainly of oxalate-containing plants such as sorrel or dock, a sudden change in diet or long spells of overcast weather.
The disease strikes suddenly and usually affects a number of animals in the flock. Stock go down suddenly and may show any of the following signs: neck turned back, muscle weakness, paralysis, muscle tremors, "proppy" gait with head held high, staggering, going down and refusing to rise, falling over when stood up and possible vaginal prolapse. If the affected animal is not treated quickly it may well die within a few hours.
The affected animal will respond quickly to an injection of commercial calcium solution at the recommended dose rate if given early enough in the course of the disease. Consult your veterinarian regarding the best options for diagnosis and treatment. A number of other conditions can look very similar.
Finely ground limestone (calcium carbonate) can be added when feeding grains which are low in calcium (1 - 1.5% of limestone to the weight of grain).
Avoid pre-disposing circumstances listed above.