Milk Fever in Cows: Signs, Causes, Treatment and Prevention Guide

A high-yielding crossbred cow calves, and within hours she is on the ground and cannot get up. Her legs are limp, her head is turned back towards her side, and she looks almost dead. Farmers who call an experienced veterinarian quickly usually see her on her feet again after treatment. The condition is milk fever, and The Agro News published this guide to it in April 2025.

This guide explains what milk fever is, why it strikes around calving, which cows are most at risk, how its signs progress, how veterinarians treat it and why that treatment must be left to them, and how feeding in the weeks before calving helps prevent it. Its facts come from veterinary authorities and research published before April 2025.

Milk fever is the common name for parturient hypocalcaemia, a sharp fall in blood calcium around calving. Despite the name, the cow has no fever. The University of Wisconsin-Madison Division of Extension lists a decreased body temperature among its signs, and an affected cow's ears feel cold. It is a metabolic disorder, not an infection, so it does not spread from cow to cow.

Calcium does far more than build bones. The Wisconsin extension educators explain that it is needed to make milk and for normal muscle contraction and nerve impulses. When blood calcium drops too far, the muscles stop working properly, so an affected cow first trembles, then staggers, and finally cannot stand.

The disorder is common wherever high-yielding dairy cows are kept. Peter D. Constable, a veterinary internal medicine and nutrition specialist, wrote in conference proceedings published by dvm360 in August 2011 that periparturient hypocalcaemia is a common condition of dairy cows with an annual incidence of 5 to 8 per cent. Jesse P. Goff of the US Department of Agriculture's Agricultural Research Service, reviewing the disorder in The Veterinary Journal in 2008, described milk fever as life-threatening to the cow and noted that it predisposes her to a variety of other disorders.

A cow draws calcium from two places: her feed and her bones. According to the Wisconsin extension fact sheet on the fresh cow, published in October 2023, the sudden rise in milk production after calving increases her need for calcium by 400 per cent compared with the dry period. Milk fever occurs when blood calcium is used up faster than it is replaced.

Colostrum, the first milk, makes the demand especially sharp. A study by Chiwome and colleagues in the Journal of the South African Veterinary Association in 2017 notes that colostrum contains approximately four times more calcium than normal milk.

Hormones decide how fast calcium is released from bone and absorbed from the gut. Goff's 2008 review focuses on parathyroid hormone, which drives that process, and on how the mineral balance of the diet before calving changes the tissues' sensitivity to it. He also identified low blood magnesium, from too little magnesium in the feed or poor absorption, as a major risk factor.

Vitamin D matters as well: Constable explains that the small intestine absorbs calcium through a mechanism regulated by vitamin D.

The Wisconsin extension fact sheet lists these risk factors:

• Cows five years old or older.
• High-producing cows.
• The Jersey breed. Jersey cattle have fewer vitamin D receptors than Holstein cattle, and vitamin D is needed to absorb calcium and phosphorus from the intestine.
• Cows that have had hypocalcaemia before.
• Diets high in potassium and calcium before calving.
• High calcium intake before calving followed by low calcium intake after calving, because of the diet or poor feed intake.
• Low roughage intake.

Research bears out the breed, age and yield effects. The Zimbabwe study covered 1,278 calvings over three years on a dairy farm at Beatrice, about 50 km south of Harare. Milk fever followed 14.78 per cent of Jersey calvings but 4.82 per cent of Holstein calvings. After the fourth calving the rate rose to 24.85 per cent in Jerseys and 8.29 per cent in Holsteins. The highest yielders were hit hardest: 27.07 per cent of Jerseys producing more than 6,114 litres in a 305-day lactation, and 10.49 per cent of Holsteins producing more than 9,149 litres.

A 2021 study in the journal Animals by Vagnoni, Oetzel and colleagues found the same pattern in blood tests: serum calcium 12 to 24 hours after calving was lower in Jerseys than in Holsteins, and lower in cows calving for the third time or more than in those calving for the second time.

Bangladesh has spent decades improving its cattle for milk. Banglapedia, the national encyclopaedia, records that Holstein-Friesian, Jersey, Sahiwal, Sindhi and other exotic breeds were brought in to cross with local zebu cattle. It gives about 1,800 litres per lactation for the Friesian cross, against an average of about 206 kg per lactation for local cows, and notes that pure and crossbred cattle have higher nutritional needs and are more susceptible to disease than the local variety.

The stakes are large. In the Department of Livestock Services (DLS) figures for fiscal year 2023-24, the country had 250.13 lakh cattle and produced 150.44 lakh tonnes of milk.

Bangladeshi researchers have found calcium problems common around calving. A team from Bangladesh Agricultural University (BAU) in Mymensingh, reporting in the Journal of Advanced Veterinary and Animal Research in June 2022, followed cows in Fulbaria upazila of Mymensingh and Nakla upazila of Sherpur. Most animals had low serum calcium in the period around calving, 8.13 ± 1.2 mg/dl on average. The team also cited an earlier Bangladeshi study of crossbred dairy cows that had recorded a milk fever prevalence of 30 per cent.

In that BAU project, cows found by routine testing to have low calcium, ketones in the urine or mastitis were treated at once. Milk fever cases fell from 17, or 11.72 per cent of 145 animals, before the programme to 8, or 3.43 per cent of 235 animals, afterwards. The share of study animals with metabolic diseases fell from 51.7 per cent to 15.3 per cent.

Another BAU team, writing in BMC Research Notes in June 2022, tested 29 crossbred cows on an organised dairy farm in Gazipur district before and after calving. Subclinical hypocalcaemia, low calcium without visible signs, affected 31.03 per cent of them, and older cows with high body condition and high milk yield were the most affected.

A third study, published in Tropical Animal Health and Production in March 2023 by researchers from BAU, the Bangladesh Livestock Research Institute (BLRI) and others, surveyed 265 dairy farms in Sirajganj, Bogura, Rangpur, Satkhira and Munshiganj and linked repeat breeding to nutritional deficiency diseases such as milk fever.

Wisconsin extension says most cases occur between calving and about three days after it, as milk production begins. It defines clinical milk fever as blood calcium below 5.0 mg/dL and divides it into three stages by severity:

• Stage 1, the cow is still standing. This stage is often missed because it is short. Signs include loss of appetite and a sluggish gut, excitability, nervousness, hypersensitivity, cold ears, weakness, shifting of weight and shuffling of the hind feet. The Merck Veterinary Manual adds fine tremors over the flanks, ear twitching and head bobbing.
• Stage 2, the cow is down. This can last 1 to 12 hours. She lies with her head tucked towards her flank and looks dull and listless, with cold ears, a dry nose and trembling muscles. Her digestive system goes quiet and she is constipated. Body temperature falls and the heart beats fast, often above 100 beats a minute.
• Stage 3, the cow cannot stand and gradually loses consciousness. Merck describes her lying flat on her side with extreme muscle slackness and severe bloat, and warns that an untreated cow at this stage may survive only for hours.

There is also a hidden form. The Wisconsin fact sheet, citing University of Florida research, says cows with blood calcium above 5.0 but below 8.5 mg/dL 12 to 24 hours after calving have subclinical milk fever and show no outward signs. It reports that 73 per cent of cows in their third or later lactation have had subclinical hypocalcaemia. It is best confirmed in a laboratory.

Diagnosis rests on the history, such as a recent calving in an older or high-yielding cow, and on the signs. The Merck Veterinary Manual notes that diagnosis is often based on clinical examination and on the cow's response to treatment, and that a blood sample taken before any intravenous calcium can be sent for calcium analysis if she does not respond.

Other conditions can keep a cow down after calving, among them severe mastitis or uterine infection, a fractured pelvis, nerve damage during calving and low magnesium or phosphorus, Merck notes. Telling them apart needs a veterinarian.

The cost goes beyond the medicine. Wisconsin extension estimates that each clinical or subclinical case of milk fever costs about $150 in the United States, because the disorder is associated with retained placenta, ketosis, mastitis, uterine infections and fatty liver. Milk yield also falls while the cow is sick, as the original story notes.

The original story's first advice still stands: call an experienced veterinarian as soon as the signs appear. Wisconsin extension advises every herd to agree a treatment protocol with its veterinarian in advance.

The standard treatment for a cow that is down is calcium given slowly into a vein. Constable wrote in 2011 that the usual treatment is 500 ml of 23 per cent calcium borogluconate by slow intravenous injection, which supplies 10.7 grams of calcium, with the heart monitored during the infusion because calcium can cause abnormal heart rhythms.

Constable also explains that calcium given under the skin must be spread over several sites, with no more than 125 ml in one place, and that calcium chloride should not be injected under the skin because it damages the tissue.

Getting the amount right matters both ways. The original story warned that a cow given too little calcium may not recover or stand, or may recover briefly and go down again, while too much given too fast into a vein can kill her. Choosing the product and amount and watching the heart during the infusion are why the authorities leave the injection to a veterinarian. Farmers should not inject calcium into a vein themselves.

Wisconsin extension, citing the University of Minnesota's veterinary school, says the deciding question is whether the cow is standing. A standing cow with early signs should not be given calcium into a vein; she can absorb what she needs by mouth. Citing Dr Gary Oetzel of the University of Wisconsin School of Veterinary Medicine, the fact sheet recommends one oral calcium bolus at calving and a second 12 hours later. It also cites a Netherlands study which found that intravenous calcium given to a cow with no symptoms can cause a short-term oversupply followed by a longer drop in blood calcium.

For a cow that is down, once she has responded to intravenous treatment by standing, the fact sheet recommends one oral bolus when she stands and a second 12 hours later, to help keep her up. If she does not respond to the intravenous treatment, it warns against giving boluses, because her muscles may not yet be working and she could choke; the farmer should seek veterinary guidance instead. Constable likewise writes that oral calcium solutions should only be given to cattle that can swallow normally, which rules them out for animals with advanced signs.

The product, the number of doses and the timing of any follow-up are decisions for the veterinarian who examined the cow. A farmer's part is to call early, keep the cow comfortable and safe until help arrives, report how she responds, and not to pour liquids into the mouth of a cow that is down.

Prevention is better than cure, as the original story says, and the authorities agree. Wisconsin extension says nutritional management during the dry period and early lactation has brought clinical cases down to less than 1 per cent in herds that apply it.

The key change is in what the cow eats in the last weeks before calving. Wisconsin extension recommends feeding close-up dry cows diets low in calcium and low in potassium before calving to help minimise hypocalcaemia, and it lists pre-calving diets high in potassium and calcium as a risk factor. The original story's warning fits this: a cow given plenty of calcium in late pregnancy comes to rely on her gut, and her bones are slow to release calcium when calving brings a sudden demand.

The same sources point to these steps:

• Supply enough magnesium. Magnesium plays an important role in keeping calcium in balance, so higher dietary magnesium before calving can lower the risk (Wisconsin extension), and low magnesium is a major risk factor (Goff, 2008).
• Consider a low DCAD diet, worked out by a nutritionist or veterinarian. Feeding anionic salts for 21 days before calving and properly managing a low dietary cation-anion difference diet has been shown to reduce subclinical hypocalcaemia (Wisconsin extension). Constable writes that such rations fed for at least two weeks before calving decrease the incidence, and that checking urine pH lets the farm see whether the diet is working.
• Keep roughage intake up, since low roughage intake is a listed risk factor.
• Give extra attention around calving to older cows, high yielders, Jerseys and cows that have had milk fever before.

Testing helps too. The BAU study in Mymensingh and Sherpur showed that routinely checking serum calcium and urine ketones around calving and treating problems at once cut milk fever cases by 70.28 per cent. The Gazipur study found no significant difference in serum minerals between cows given calcium and magnesium injections on the day of calving and cows not given them, when all were fed a balanced ration.

A cow that cannot stand after calving is an emergency. In Bangladesh the first call should go to the upazila livestock office of the Department of Livestock Services, which runs the government's veterinary services at upazila level, or to a registered veterinarian. Tell them when the cow calved, whether she can stand and whether she can swallow.

For prevention, ask the livestock officer or a dairy nutritionist to check the ration of cows due to calve, especially older, high-yielding and Jersey-cross cows.

Photo: Ibrahim Husain Meraj / Wikimedia Commons (CC BY-SA 3.0)

Sources: The Agro News (staff correspondent), University of Wisconsin-Madison Division of Extension (The Fresh Cow: Milk Fever), dvm360 (Peter D. Constable, Milk fever: new approaches to treatment and control), The Veterinary Journal (Goff, 2008), Journal of the South African Veterinary Association (Chiwome et al., 2017), Animals (Vagnoni et al., 2021), Journal of Advanced Veterinary and Animal Research (Ahammed et al., 2022), BMC Research Notes (Kabir et al., 2022), Tropical Animal Health and Production (Islam et al., 2023), Banglapedia, Department of Livestock Services, Merck Veterinary Manual