Milk Fever (Hypocalcaemia) in Dairy Cattle: Causes, Treatment & Prevention

By Vrap · Published Mon May 18 2026 00:00:00 GMT+0000 (Coordinated Universal Time) · Updated Mon May 18 2026 00:00:00 GMT+0000 (Coordinated Universal Time)

What is milk fever?

Milk fever is a sudden, serious disease that strikes dairy cows and buffaloes right after calving — usually within 24 to 72 hours of giving birth. The cow goes down, cannot stand, and without quick treatment, can die within a day.

Despite the name, milk fever has nothing to do with fever. The body temperature is usually normal or below normal. The real name is hypocalcaemia — meaning low blood calcium.

The cause is simple to understand: when a cow starts producing colostrum and milk after calving, her body suddenly needs to put huge amounts of calcium into the milk. A healthy cow's calcium store is in her bones. But moving calcium from bones to blood takes a few days. In those few days, the blood calcium drops below safe levels, and the muscles stop working.

This article explains why milk fever happens, the three stages of symptoms, how it is treated, and most importantly, how to prevent it.

Why milk fever happens — simple explanation

Think of calcium in the cow's body in two pools:

• The blood pool — small but always in use (for muscles, nerves, milk)
• The bone pool — large reserve

When the cow calves, her milk production starts immediately. Colostrum is very rich in calcium — much higher than regular milk. A 500 kg cow may need to put 30–50 grams of calcium into her colostrum and early milk every day.

The blood pool gets drained fast. Normally, the body releases calcium from the bones to keep blood calcium steady. But:

• This release takes 2–3 days to fully start
• Older cows release calcium more slowly than younger ones
• High-yielding cows need more calcium than the bones can release fast
• If the cow was eating too much calcium before calving, her body has gotten "lazy" — the calcium release system has shut down because it wasn't needed

The result: blood calcium drops from normal (9–10 mg/dl) to dangerous (below 6 mg/dl). At this level, muscles cannot function. The cow goes down.

Who is at high risk?

Five factors increase risk:

Young first-calf heifers rarely get milk fever — their bones release calcium readily. After 3rd or 4th calving, the risk goes up significantly.

The three stages of milk fever

Recognising milk fever early can save your cow. There are three stages:

Stage 1: Early (often missed)

• Cow is restless, walking strangely
• Slightly weak in the back legs
• Muscle tremors in legs and shoulders
• Loss of appetite, not eating fully
• May appear slightly nervous

This stage lasts 1–2 hours. Most farmers miss it because the cow is still standing.

Stage 2: Classic milk fever (most common)

• Cow cannot stand — even if she tries
• Lies on her chest with head turned back toward flank (this is the classic position)
• Ears and legs feel cold
• Eyes are slightly sunken
• Body temperature is normal or slightly below (35–37°C)
• Quiet, may seem sleepy
• Stops eating completely

This stage is unmistakable. The "head turned to flank" position is the textbook sign.

Stage 3: Emergency (life-threatening)

• Cow is lying on her side (not on her chest anymore)
• Unconscious or barely responding
• Slow breathing, weak pulse
• Cold body, glazed eyes
• Bloated rumen

Stage 3 is a medical emergency. Without immediate treatment, the cow will die within hours.

How milk fever is treated

The only effective treatment is intravenous calcium, given by a veterinarian.

What the vet does

1. Examines the cow — confirms milk fever vs other conditions
2. Gives 400–500 ml of 25% calcium borogluconate solution slowly into the jugular vein
3. Watches for response — heart rate, breathing, return of muscle function
4. Sometimes adds magnesium and phosphorus to the IV solution
5. Repositions the cow so she is on her chest (not flat on her side)
6. May give a second dose 6–12 hours later if response is partial

What happens after treatment

Most cows respond within 15–30 minutes of the calcium IV:

• Muscle tremors return (a good sign — muscles are working again)
• Cow lifts her head
• Within 30–60 minutes she may try to stand
• Many cows are eating and acting normally within 2 hours
• Some need a second IV dose

Why NOT to give IV calcium yourself

It is tempting to keep IV calcium on the farm and give it yourself. This is dangerous:

• Too-fast injection can cause heart failure (this is the leading cause of milk-fever-treatment death)
• Calcium given to a non-deficient cow can also cause heart failure
• Missing the vein can cause severe tissue damage (calcium leaking under the skin causes a hard, painful lump that can become infected)
• Without diagnosis, calcium might not be the right treatment

Always call a veterinarian. Costs ₹500–2,000 for the visit and treatment, vs ₹40,000+ for a dead high-yielding cow.

What about oral calcium boluses?

Oral calcium boluses (large pills that contain calcium chloride or calcium propionate) are useful for:

• Mild stage 1 cases — when the cow is still standing
• Prevention in high-risk cows — given just before and after calving
• Follow-up after IV treatment — to maintain calcium levels

Standard protocol: one bolus at calving, one 6–12 hours after, one 24 hours after, one 36 hours after — four doses total for high-risk cows.

Cost: ₹150–400 per bolus. A 4-bolus protection plan costs ₹600–1,600 per cow — very low compared to the disease cost.

Prevention — the dry period is the key

Prevention is dramatically cheaper than treatment. The key is how you feed the cow in the last 2–3 weeks before calving (called the "close-up dry period").

Rule 1: Don't over-feed calcium before calving

Many farmers think that giving extra calcium-rich feed before calving prepares the cow. This is backwards. When you give a cow extra calcium, her parathyroid hormone system shuts down — because it doesn't need to release calcium from bones. Then when she calves and suddenly needs huge calcium release, the system can't switch back on fast enough.

The right approach in the close-up dry period (last 2–3 weeks):

• Limit calcium-rich forages — reduce or skip berseem and lucerne; use grass-based green fodder instead
• Limit calcium-rich mineral supplements — switch to a low-calcium dry-cow mineral mixture
• Limit limestone supplements in the concentrate

The goal: keep daily calcium intake moderate, not high, in the last 2–3 weeks. This trains the parathyroid system to release calcium from bones — exactly what the cow needs at calving.

Rule 2: Provide enough magnesium

Magnesium is needed for the parathyroid hormone to work. Without enough magnesium, even a calcium-deficient cow cannot release her bone calcium.

Standard inclusion: magnesium oxide at 30–50 g/day during the dry period, or a mineral mixture with 5%+ magnesium content (the NDDB standard mineral mixture meets this).

Rule 3: Vitamin D supplementation

Vitamin D helps calcium absorption from the gut. Indian dry-period cows benefit from:

• Sunlight exposure (Indian sun is plentiful — let the cow into open lots)
• Vitamin D injection 3–5 days before expected calving (vet-administered)
• Vitamin AD3E premix in the concentrate (already in good mineral mixture)

Rule 4: Anionic salts (advanced prevention)

For high-yield commercial dairies, anionic salt diets (also called DCAD — Dietary Cation-Anion Difference) are the gold-standard prevention. The idea: give the cow a slightly acidic ration in the last 2–3 weeks of pregnancy. This forces the body to release calcium from bones even before calving, "training" the system to be ready.

Anionic salts (ammonium chloride, magnesium chloride, calcium chloride) are mixed into the dry-period concentrate at 100–200 g/day. This is technical and requires veterinary guidance. Not for smallholder farms.

Rule 5: Oral calcium boluses at calving

For known high-risk cows (older, high-yielding, history of milk fever), give 4 oral calcium boluses spaced over 36 hours starting at calving. This is the simplest, most affordable prevention for individual high-risk animals.

Special considerations for buffaloes

Milk fever in buffaloes follows the same pattern as in cows:

• High-yielding Murrah, Jaffrabadi, Mehsana, Surti buffaloes are at risk
• Symptoms and treatment identical to cows
• Prevention is the same — careful dry-period feeding

One difference: buffaloes may show subclinical hypocalcaemia more often than cows (calcium low but no obvious symptoms). The cow drops yield by 1–2 L/day but doesn't go down. Many Indian buffalo dairies experience this without diagnosing it. Routine prevention through good dry-period management catches both clinical and subclinical cases.

Distinguishing milk fever from other dairy diseases

Several diseases can cause a recently-calved cow to go down. Tell them apart:

Milk fever has the unique signature: very recent calving (under 72 hours) + cannot stand + head turned + cold ears + no fever. If unsure, call the vet — milk fever is too dangerous to wait on.

Cost-benefit of prevention

The ROI on milk fever prevention is 5–10× the cost for high-risk cows.

Common milk fever mistakes on Indian dairies

1. Over-feeding green fodder (especially legumes) in late pregnancy — too much dietary calcium suppresses bone release
2. Not differentiating dry cow ration from lactating ration — most dry cows in smallholder farms get the same feed as milking cows
3. Skipping mineral mixture in the dry period — leads to magnesium deficiency at calving
4. Self-treating with IV calcium — heart attack risk; vet is essential
5. Not recognising stage 1 symptoms — early oral bolus treatment can prevent stage 2
6. No oral calcium ready for high-risk cows
7. Assuming young first-calf heifers are at risk — they are not; the disease is older-cow specific

A practical prevention plan for a dairy farm

For a dairy with mixed-age cows, here is a simple plan:

Standard cows (1st-2nd calving)

• Normal feeding through pregnancy
• Switch to dry-cow ration last 60 days
• Normal mineral mixture
• No special bolus needed

High-risk cows (3rd+ calving, or yielded 15+ L/day previous lactation)

• Switch to dry-cow ration last 60 days
• Last 21 days: restrict berseem/lucerne; use grass-based forage
• Daily magnesium oxide supplement
• Vitamin D injection 3–5 days before expected calving date
• At calving: first oral calcium bolus immediately
• 12 hours later: second bolus
• 24 hours later: third bolus
• 36 hours later: fourth bolus

Previous milk fever cows

• Same as high-risk PLUS
• Vet inspection in late pregnancy
• Continuous monitoring first 72 hours post-calving
• Calcium and vitamin D injection if any stage-1 sign appears

Conclusion

Milk fever is dangerous, but it is also highly preventable. The science is simple — keep dietary calcium moderate before calving (not high), provide adequate magnesium and vitamin D, and use oral calcium boluses for high-risk cows. Total prevention cost per cow per calving is ₹800–1,800; expected loss per case is ₹8,000–20,000 or more.

Watch the cow carefully in the first 72 hours after calving — this is the window when milk fever strikes. The classic symptoms (cannot stand, head turned to flank, cold ears) are unmistakable. Call a vet immediately for IV calcium — never self-administer.

Most importantly, train yourself to recognise stage 1 symptoms (slight restlessness, weakness, tremors). At this stage, oral calcium bolus and immediate vet consultation can prevent the full disease — much cheaper and safer than the emergency response to a stage 2 or 3 case.

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