Hypocalcemia is one of the most common disorders affecting dairy cows at the onset of lactation. It is characterised by decrease in blood calcium below normal level. Stricken cows may have it with symptoms (clinical hypocalcemia or milk fever) or without symptoms (subclinical hypocalcemia). Ionised calcium (iCa) is the physiologically active form of calcium in blood. It reflects more accurately the current calcemic blood situation compared to total blood calcium as it equals the free available calcium ions. By measuring the ionised calcium levels of blood samples directly cow-side, the treatment of dairy cows can start sooner preventing debilitating symptoms or complications. The new LAQUAtwin Ca-11C has been specially developed for cow-side measurement of ionised calcium in blood. It is ideal for screening dairy cows for hypocalcemia.