Milk Fever in Cows: Symptoms, Prevention, and Monitoring to Safeguard Dairy Yield

The sharp surge in milk production post-calving drastically increases the cow's demand for calcium. If this need is not met promptly, the dairy cow may collapse due to hypocalcemia. This condition is the frustrating "milk fever" that plagues dairy farmers. The incidence rate in US dairy herds is approximately 6%, with 75% of cases occurring within 24 hours postpartum and the remaining cases showing symptoms in the following 48 hours. More severely, low blood calcium can also lead to dystocia (difficult birth), impacting both the cow's health and productivity. This article provides a comprehensive analysis of this challenging condition, covering its causes, symptom identification, prevention and treatment strategies, and the latest monitoring techniques, to help you more effectively safeguard your herd's health.
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What is Milk Fever? Postpartum Hypocalcemia Common in Dairy Cows

Milk Fever is a metabolic disorder that occurs in lactating cows around the time of or shortly after calving. It is primarily triggered by a sharp drop in blood calcium concentration, and is also known as postparturient hypocalcemia or parturient paresis. Although the term "fever" is used, the disease does not actually cause an elevated body temperature; its defining feature is the drop in blood calcium concentration (hypocalcemia). Milk fever is most common in the immediate postpartum period because cows require a large amount of calcium to produce colostrum and milk. When this demand exceeds the body's supply, milk fever is highly likely to occur if sufficient calcium is not supplemented.

Abnormal Cow Status? Rapid Identification of Clinical and Subclinical Milk Fever Symptoms

Milk fever can be classified into clinical and subclinical types, with the clinical form further divided into three progressive stages. By detailing the progression of the disease, farmers can quickly grasp the cow's health status and make timely judgments.

Clinical Milk Fever Symptoms: A Three-Stage Progression

Stage 1 Clinical Signs

At this stage, the cow is still able to stand but exhibits signs of hypersensitivity or excitement, such as trembling, ear twitching, head bobbing, and mild ataxia (incoordination). These are crucial warning signs of milk fever; without timely calcium supplementation or treatment, the condition often progresses to Stage 2.

Stage 2 Clinical Signs

The cow is now unable to stand and presents in the classic milk fever posture: lying in sternal recumbency (breastbone on the ground) with its head typically tucked toward its flank. A noticeable drop in body temperature can be observed, and the limbs feel cold; the heart rate is significantly fast (tachycardia), but the pulse is weak. Due to the paralysis of smooth muscle caused by hypocalcemia, the cow appears dull and listless, gastrointestinal motility slows down, and it may be accompanied by mild bloat or difficulty urinating and defecating.

Stage 3 Clinical Signs

The cow changes from sternal recumbency to lateral recumbency (lying on its side), indicating muscle flaccidity, unresponsiveness to external stimuli, and loss of consciousness progressing to coma. The heart rate can reach approximately 120 beats per minute, and peripheral pulses are weak to almost undetectable. If emergency treatment is not provided, milk fever rapidly worsens, with approximately 60%–80% of cows potentially dying; cows in Stage 3 may only survive for a few hours.

Subclinical Milk Fever Symptoms: Incidence Far Exceeds the Clinical Form

The incidence of subclinical milk fever is much higher than the clinical form, yet it is often severely underestimated. Although affected cows can still stand and move normally, insufficient blood calcium compromises their productive efficiency and increases the risk of mastitis and metritis (uterine infection). For dairy farmers, effectively reducing the number of subclinical cases not only improves cow health but also significantly boosts the overall productivity of the dairy farm.

Don't Let "Hypocalcemia" Undermine the Farm! The Unignorable Chain Crisis of Milk Fever

Milk fever is not merely a simple nutritional deficiency-induced hypocalcemia. If not treated in time during Stage 1 clinical signs, the cow can rapidly deteriorate into a paralytic state, facing a mortality risk as high as 90%, while also greatly increasing culling rates and leading to massive economic losses. Although subclinical milk fever shows no obvious symptoms, it weakens the immune system, inducing multiple health issues such as mastitis, uterine infections, and retained placenta. Concurrently, it reduces milk yield, increasing the farm's burden in terms of time, labor, and cost, causing long-term effects on operational efficiency.

Milk Fever Response Guide: Key Prevention and Treatment Strategies for Protecting the Herd

The core of milk fever prevention lies in feed management during the pre- and postpartum periods and regular blood monitoring. Once signs of the disease are discovered, immediate supplementation with calcium and glucose is necessary. Since milk fever is often accompanied by elevated blood ketones and hypoglycemia, farmers can use blood tests as a basis for early diagnosis, effectively reducing health risks for the cows.
〈Related Article: How Does Bovine Ketosis Affect Milk Production? Understand the Causes and Symptoms to Prevent It!〉

Postpartum Feed Management: Low-Calcium Diet Prevents Hypocalcemia

The cow's dry period (50–60 days before calving) is a critical transition period for nutritional management, influencing not only postpartum lactation performance but also subsequent breeding efficiency. Therefore, milk fever prevention should start during the dry period by feeding a low-calcium or acidified diet, which can effectively reduce the cow's risk of developing hypocalcemia. Specifically, feeding an acidified diet for about three weeks before calving causes a compensatory metabolic acidosis in the cow, which enhances intestinal calcium absorption, improves the responsiveness of parathyroid hormone (PTH) receptors, and promotes the mobilization of more calcium from the bones.

How to Quantify Dairy Cow Feed Acidity? An Easy Calculation with DCAD

The Dietary Cation-Anion Difference (DCAD), calculated in milliequivalents (mEq) as Na + K) - (Cl + S), measures a feed's ability to induce an acidic or alkaline reaction. Feeding a diet with a DCAD ranging from -50 to $-150 mEq/kg of dry matter (DM) pre-calving is the most ideal target range for preventing post-calving paralysis, known as milk fever in cows.

Milk Fever Treatment: Calcium Supplementation Based on Disease Stage

The most crucial step in treating milk fever is immediate calcium supplementation, typically via intravenous (IV) injection of calcium gluconate, to help the cow restore normal neuromuscular function. Additionally, glucose is supplemented concurrently during the onset to maintain blood sugar levels. Different calcium supplementation methods can be employed at various stages:

Stage 1 Cows (Still Standing): Oral Calcium Supplementation

For Stage 1 milk fever, oral calcium supplements are recommended. Oral calcium is rapidly absorbed into the bloodstream and rarely causes hypercalcemia or rebound hypocalcemia. Acidifying calcium sources, such as oral formulations of calcium chloride or calcium sulfate, are typically selected. These calcium sources quickly elevate blood calcium and promote the cow's ability to regulate calcium balance by enhancing parathyroid hormone (PTH) receptor responsiveness.

Stage 2 and 3 Cows (Recumbent/Down): Intravenous Calcium Injection

Cows that are recumbent (lying down) in Stage 2 or Stage 3 milk fever require immediate intravenous calcium correction. The standard treatment is 500 mL of a 23% calcium gluconate solution, containing the stabilizer boric acid, which provides 10.7 grams of elemental calcium and rapidly restores blood calcium concentration. During treatment, the injection rate must be carefully controlled to avoid rapid heart rate (tachycardia) and shock. The cow's response should be closely monitored, and the injection may be repeated if necessary.

Say Goodbye to Traditional Blind Testing! How a Blood Calcium Meter Precisely Catches Subclinical Milk Fever in Cow

Traditionally, most dairy farmers rely on observing symptoms or using urine test strips to assess a cow's blood calcium, but these methods have limited accuracy. Overseas, although diet adjustments based on urine pH are often used to prevent milk fever, the actual effect is often unsatisfactory, providing insufficient protection against hypocalcemia. Only direct measurement of serum calcium concentration can provide a precise understanding of the cow's health status.

Modern dairy farmers can utilize a blood calcium meter for quick and accurate on-site measurement of blood calcium. The risk is highest during early lactation, where blood calcium concentration may drop below 8.5mg/dL. Using a blood calcium meter enables early diagnosis of milk fever and intervention at the first stage, reducing the risk of disease progression and yield loss.

Why Monitor Blood Ketones in Milk Fever Cows? Unveiling the Metabolic Disease Chain Reaction

Milk Fever is caused by "hypocalcemia" (low blood calcium), so why is it necessary to also monitor "blood ketones (BHB)"?

The answer is: because hypocalcemia is the key catalyst that triggers ketosis. These two diseases in high-producing dairy cows around calving are closely intertwined, representing a chain reaction of the "metabolic disease complex":
 

1. Hypocalcemia Leads to Paralysis: The core of milk fever is critically low blood calcium, causing weakness in all muscles (including skeletal and smooth muscles). This not only results in the cow becoming recumbent (clinical symptom) but also creates an invisible, fatal problem.
2. Rumen Motility Stops: The cow's rumen is composed of smooth muscle. Low blood calcium causes rumen paralysis, halting its movement.
3. Feed Intake Plummets: With the rumen stopped, the cow loses its appetite. For a cow that has just calved and desperately needs a massive amount of energy for lactation, stopping feed intake immediately results in a Negative Energy Balance (NEB).
4. Ketosis is Triggered: To compensate for the enormous energy deficit, the body begins to aggressively break down body fat. This process generates large quantities of byproducts—ketone bodies (BHB)—in the liver. When ketones accumulate faster than the body can utilize them, ketosis erupts.
    

In simple terms, this vicious cycle is: Hypocalcemia (Milk Fever) → Muscle Weakness → Rumen Stasis → Decreased Feed Intake → Severe Negative Energy Balance → Excessive Fat Breakdown → High Blood Ketones (Ketosis).

This is why many cows, although able to stand up after receiving IV calcium (milk fever treatment), remain listless with a poor appetite and severely compromised milk yield: the secondary ketosis induced by milk fever was not detected and addressed. Therefore, monitoring blood ketones (BHB) is the critical indicator for determining whether a milk fever cow has truly escaped the metabolic storm and recovered its health.

The SANcheck Monitoring System for Milk Fever Defense: Drawing a Line Against Metabolic Diseases!

Cows around calving face a complex metabolic chain storm; simply treating hypocalcemia (milk fever) is not enough. You must also manage the crises of secondary ketosis and hypoglycemia that it triggers. Traditionally, farmers only become aware of ketosis when the cow is depressed and completely off-feed, but by that point, permanent damage to milk yield has often occurred. The SANcheck ABEL Vet GK Blood Glucose and β-ketone (BHB) Monitoring System for dairy cows, designed specifically for cattle, was created for this purpose. It helps you establish the most critical metabolic line of defense at the frontline:
 

1. Real-time Blood Ketone (BHB) Measurement: When treating a cow for milk fever (whether clinical or subclinical), immediately use SANcheck to check its blood ketone level. This helps you determine if the cow has developed concurrent ketosis due to decreased feed intake. Early detection (e.g., BHB > 1.2 mmol/L) allows for timely energy intervention (such as propylene glycol drenching) to prevent disease deterioration.
2. Synchronous Blood Glucose (Glucose) Monitoring: High blood ketones are often accompanied by low blood glucose. Monitoring blood glucose simultaneously provides a more comprehensive understanding of the cow's energy status, helping to determine if immediate glucose supplementation is needed to support the cow's return to feeding.
3. Fast, Accurate, and Easy to Track: Accurate blood ketone and glucose data can be obtained cow-side in just a few seconds (ketones approx. 10 seconds, glucose approx. 5 seconds), eliminating the need to send samples to a lab. The instrument's built-in data storage function further helps you track high-risk groups over the long term, ensuring they transition smoothly through the critical post-calving period.
    

Stop waiting until the cow goes down to act. Through the SANcheck detection system, you can "see" this invisible killer in the early stages of milk fever-induced ketosis, blocking the vicious cycle of metabolic disease at its root and truly protecting herd health and farm productivity.
<Product Recommendation: SANcheck ABEL Vet GK Blood Glucose and β-ketone (BHB) Monitoring System>

Conclusion

In summary, a down cow is often more than just milk fever; complex interactions between blood calcium, blood glucose, and blood ketones may be involved. Relying on a single diagnostic indicator often means that by the time symptoms appear, it is already too late. The General Life Biotechnology SANCheck ABEL Vet GK Blood Glucose and β-ketone (BHB) Monitoring System can simultaneously measure blood ketones (range 0.1–8  mmol/L) and blood glucose (range 20–600 mg/dL), helping dairy farmers instantly grasp subtle changes in the cow's condition. This enables early detection of secondary ketosis triggered by milk fever and prevents disease progression. Contact us now to learn how scientific monitoring can safeguard your farm's health.
〈Related Article: What is Equine Metabolic Syndrome (EMS)? Understanding the Symptoms and Management Strategies 〉
〈Related Article: What is Equine Infectious Anemia (EIA)? A Quick Guide to Symptoms, Testing Methods, and Key Prevention〉

References
Milk fever
乳牛營養代謝疾病與繁殖障礙之關係―乳熱病
Parturient Paresis in Cows
Ketosis: prevention is better than cure
subclinical milk fever