Milk Fever Hypocalcaemia After Calving
Milk fever, or parturient paresis, is a metabolic disorder of high-producing cows and buffalo in the first 48 hours after calving, caused by a sudden fall in blood calcium as milk secretion begins. The cow drains calcium into colostrum faster than bone can replace it, so trembling and weakness progress to recumbency. It responds quickly when caught early but can kill within hours if treatment is delayed, and it returns in later seasons when dry-period feeding is not corrected.
Why calcium falls at calving
Calcium is essential for muscle contraction and nerve signalling. Late pregnancy places heavy demand on the dam, then the parathyroid gland secretes hormone to mobilise calcium from bone. If the cow is overfat or has been fed a high-calcium dry diet, hormone receptors become less responsive, the response is delayed, and the animal cannot cover the deficit at the critical moment.
Risk factors include the third to sixth lactation, high milk yield, sensitive breeds such as Jersey and Holstein, overconditioning at calving, magnesium deficiency that impairs hormone release, and heat stress. Buffalo are less affected than cows but are not immune, especially in high-yielding, heavily supplemented herds.
The three stages of signs
Stage one: the cow is standing but restless, muscles tremble, she refuses feed and walks stiffly with cold extremities. She may paw the ground with her hind legs and move her head repeatedly. This is the golden window, because treatment now is simple and leaves no complications.
Stage two: the cow lies on her brisket with her neck turned to the side in an S shape, with a fast weak pulse, cold ears, no rumination and mild bloat. Stage three: full lateral recumbency, loss of consciousness and severe bloat, and she may die within hours from heart failure or inhalation of rumen contents. Every stage crossed lowers the chance of success.
Treatment: speed saves the cow
The core treatment is slow intravenous calcium at the correct concentration, given by a veterinarian while pulse and breathing are monitored, because rapid injection causes arrhythmia and can kill. After the intravenous dose, oral calcium gels or subcutaneous injection stabilise the level, and the cow is warmed, bedded deeply and rolled from side to side every two hours.
A cow that does not respond after two doses needs reassessment, because the diagnosis may be metritis, muscle tear, phosphorus deficiency or a pelvic fracture. Do not give extra doses at random, since excess calcium causes arrhythmia. Follow-up for a week should cover appetite, temperature and milk yield.
Prevention during the dry period
Prevention starts a month before calving and rests on three pillars: avoid overconditioning, control dietary calcium and supply enough magnesium. During the dry period, a low-calcium diet with adequate magnesium is preferred, or a negative dietary cation-anion balance ration calculated by your veterinarian, because it primes the body to mobilise calcium from bone at calving.
Daily exercise and reduced heat stress in the final weeks lower the risk, and oral calcium at calving is given to cows with a previous history under veterinary direction. Record every case, because a cow that has had milk fever is more likely to repeat it next season. General support with mineral salts from our livestock vitamins, together with livestock and sheep and medical supplies, helps manage the herd.
- Keep body condition moderate and never fatten the cow before calving.
- Adjust calcium in the dry ration according to veterinary advice.
- Supply magnesium in the ration, especially in the final weeks.
- Check the cow every two hours during the first day after calving.
- Call the vet at once for trembling, recumbency or cold ears.
- Never inject calcium yourself; the wrong speed or dose can be fatal.
Conclusion
Milk fever is a matter of minutes, not hours, and the difference between recovery and death is catching the first tremble. Correct dry-period feeding and close attention on the first day after calving protect the high-yielding cow from this sudden collapse.
This article is general guidance and is not a substitute for examining your animal by a licensed veterinarian. In emergencies, contact your vet immediately.
