Fact Sheet: Demystifying Milk Fever in cows

Milk Fever scientifically known as Hypocalcaemi is a disease, usually in dairy cows, characterized by reduced blood calcium levels and affects over 6 percent of dairy cows globally. It is most common in the first few days of lactation, when demand for calcium for milk production exceeds the body's ability to mobilize calcium reserves.

"Fever" is a misnomer, as body temperature during the disease is usually below normal. Low blood calcium levels interfere with muscle function throughout the body, causing general weakness, loss of appetite, and eventually heart failure. Milk Fever is more common in older animals which in most cases have reduced ability to mobilize calcium from bone and in certain breeds such as Jersey cattle. It occurs occasionally at any time during the lactation or pregnancy and in many mammalian species.

In mild cases, the animal seems quite normal, but has difficulty standing. If the cow succeeds in rising, she staggers, and will very soon fall. The cow's appetite can be maintained at that stage and body temperatures at this point are from 37 to 38.5 degree celsius.

This stage, referred to as "first degree", corresponds to calcium content in blood, also known as calcemiae, of 55 to 75 milligrams of calcium per liter of blood, which is a measurement of how strong a mixture is and profiled as mg/l. In typical cases, the cow's head is in a so-called "self-auscultation" position.  The heart can be slow or arrhythmic and the body temperature ranging between 35 to 37°C. In that stage, referred to as "second degree", calcium levels in the blood are of 30 to 65 mg/l.

In advanced cases, the cow is lying on its side, seeming dead. The body temperature can go as low as 32 degrees celsius. This is the third degree, with calcemia as low as 20 mg/l. Treatment generally involves calcium injection by intravenous, intramuscular or subcutaneous routes. Before calcium injection was employed, treatment comprised inflation of the udder using a pneumatic pump.

Inflation of the udder worked because the increased pressure created in the udder pushed the calcium in the udder back into the bloodstream of the cow. Oral administration of a dose of a calcium salt in a gel have been advised by some veterinarians.

Intravenous calcium, though indicated in many cases, is potentially fatal through "heart blockade", or transient high calcium levels stopping the heart, so should be administered with care. In Some rare cases of downer cows, intravenous calcium injection can lead to diagnosis. Defecation, urination and belching are frequent during the treatment, due to pharmacological effect of calcium on the smooth muscles.

In stages 1 and 2, the cow can stand up approximately 10 minutes after the end of the intravenous injection. But in stage 3, it may take two or three hours. If the cow is in stage 3 and lying on its side, it is important to put the cow in a horizontally comfortable position or else risk aspiration.

The recovery of affected cattle after administering of the treatment is generally good, even in advanced cases. However, some cows can relapse the following day, and even a third time the day after. Proper dietary management will prevent most cases of milk fever.

This generally involves close attention to mineral and fiber levels in the diet prior to calving, as well as improving cow comfort to eliminate other problems that may interfere with appetite and so trigger Hypocalcaemia.