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 hypocalcemia). General advice is to restrict calcium intake before calving, as this leads to the parathyroid gland stimulating the release of calcium from bones. Calcium Salts
A synthetic analogue of 25-hydroxycholecalciferol can be given by injection in the days leading up to calving, although the timing of this prophylaxis makes it difficult to use.Oral administration of a dose of a calcium salt in a gel has been advised by some veterinarians. An orally administered bolus containing a much higher concentration of calcium than the injectable solutions can also be given so long as the cow is standing or sitting up. If the cow is lying flat out then immediate intravenous therapy is required to avoid death. Treatment
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.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. Cows are to be fed jaggery along with the lime water mixture. In unclear cases of downer cows, intravenous calcium injection can lead to diagnosis.
Cause
During the dry period (late gestation, non-lactating), dairy cattle have relatively low calcium requirements, with a need to replace approximately 30 g of calcium per day due to utilization for fetal growth and fecal and urinary losses. At parturition, the requirement for calcium is greatly increased due to initiation of lactation, when mammary drainage of calcium may exceed 50g per day. Due to this large increase in demand for calcium, most cows will experience some degree of hypocalcemia for a short period following parturition as the metabolism adjusts to the increased demand. When the mammary drain of plasma calcium causes hypocalcemia severe enough to compromise neuromuscular function, the cow is considered to have clinical milk fever. Mechanism
In normal calcium regulation, a decrease in plasma calcium levels causes the parathyroid glands to secrete parathyroid hormone (PTH), which regulates the activation of Vitamin D3 in the kidney. These two compounds act to increase blood calcium levels by increasing absorption of dietary calcium from the intestine, increasing renal tubular reabsorption of calcium in the kidney, and increasing resorption of calcium from bones.It has been found that tissue is less responsive to parathyroid hormone prepartum, compared to postpartum. It is believed that hypocalcemia causing milk fever is due to a lower level of responsiveness of the cows tissues to circulating parathyroid hormone.The resultant decreased plasma calcium causes hyperexcitability of the nervous system and weakened muscle contractions, which result in both tetany and paresis. Prevention
Diet
Proper dietary management will prevent most cases of milk fever.