Occurs in late pregnancy and most commonly within two days after calving in older (five years and over) cows. The cow goes down and appears semi-conscious. Some cows are more susceptible than others, and it is more prevalent in over-fat cows and where there is a high level of feeding prior to calving. It is caused by a fall in the calcium level of the blood. A bottle of calcium borogluconate injected under the skin will result in an immediate recovery unless the disease has reached an advanced stage or is complicated by grass staggers or acidosis. As a prevention, overfeeding should be avoided before calving.