Blood in Cow Milk: Causes, First Aid & Prevention

Quick answer: Blood in cow or buffalo milk (pink, red or blood-streaked milk, called haemolactia) is most often caused by small blood vessels bursting inside the udder just after calving, especially in heifers and high yielders with heavy udder swelling, and it usually clears on its own within 4–7 days. Blood that appears later in lactation, comes from one hot or hard quarter, or comes with clots, fever or a drop in appetite points to injury or mastitis and needs a veterinarian. Do not drink or sell bloody milk, milk the affected quarter gently and fully, and avoid home remedies that injure the teat.

What does blood in milk look like?

Farmers usually notice it in three ways:

• Pink or light-red milk from one or more quarters, often in the first milkings after calving.
• Red streaks or small clots in the strip cup or at the bottom of the milking bucket.
• A red or brown layer that settles at the bottom when milk is left to stand.

Note which quarter it comes from, whether that quarter is hot, hard or painful, and whether the animal is eating and has a normal temperature. This tells you, and your vet, a lot about the cause.

Common causes of blood in milk

1. Udder swelling and burst capillaries after calving (most common)

Around calving the udder fills quickly and often swells with fluid (udder oedema). Tiny blood vessels in the milk-producing tissue can rupture, and the blood mixes with the milk. This is most common in first-calf heifers and high-yielding cows and buffaloes, usually affects more than one quarter, and the animal is otherwise bright and eating. See our guide to udder oedema around calving.

2. Injury to the udder or teat

A kick, a fall on a slippery floor, a step on the teat by the animal itself, rough hand-milking (stripping with a pinched thumb), or a faulty milking machine with too much vacuum can all damage the udder and cause bleeding. Usually only the injured quarter is affected.

3. Mastitis

Some forms of mastitis damage udder tissue badly enough to cause bleeding. Suspect mastitis when blood comes with clots or flakes, watery milk, a hot, hard or painful quarter, fever or a drop in feed intake. The California Mastitis Test (CMT) is a quick way to check quarters on the farm.

4. Bleeding disorders and poisoning (less common)

Rarely, blood in milk is part of a wider bleeding problem, for example after eating mouldy sweet clover or certain toxic plants, from rat-poison exposure, or with some infectious diseases. In these cases you may also see bleeding from the nose, blood in dung or urine, pale gums or weakness. This is an emergency: call your veterinarian at once.

What to do: first steps on the farm

1. Do not use the milk. Keep milk from the affected quarter out of the bulk can. It should not be sold or used for people; ask your vet whether it can be fed to calves.
2. Milk gently and completely. Leaving milk in the quarter raises the risk of mastitis. Use full-hand milking, not thumb stripping, and check machine vacuum and liners.
3. Keep the animal calm and the floor dry. Rough handling, slippery floors and chasing can make bleeding worse.
4. Check for mastitis. Look for clots, watery milk, a hot or hard quarter, or fever, and run a CMT test if you have one.
5. Watch the trend. Post-calving blood usually becomes lighter with each milking and is gone within about a week.
6. Avoid harmful home remedies. Do not insert sticks, feathers or straws into the teat canal, and do not apply irritants to the udder.

When to call a veterinarian

• Blood continues for more than 5–7 days, or gets heavier instead of lighter.
• Blood appears in mid or late lactation, not just after calving.
• The quarter is hot, hard, swollen or painful, or the milk has clots or is watery.
• The animal has a fever, stops eating, or shows bleeding from other places.
• The same animal had blood in milk in an earlier lactation.

Your veterinarian may examine the udder, test the milk, and decide whether medicines are needed. Do not give injections or put tubes into the teat without veterinary advice.

How to prevent blood in milk

• Manage the transition period. Feed a balanced dry-cow ration, avoid overfeeding salt and concentrate before calving, and keep the cow active. See our guide to transition-period management.
• Correct minerals and vitamins. Balanced minerals and trace elements support udder tissue and immunity. A chelated mineral mixture such as Cattle Remedies Verymin helps cover common deficiencies in Indian feed and fodder (see best mineral mixture for cattle in India).
• Support udder health through lactation. Cattle Remedies Uddicin-H is a multivitamin liquid supplement with biotin and selenium that supports udder health and milk quality; it is supportive care, not a treatment for bleeding or mastitis. Compare options in our udder health supplement buying guide.
• Good milking practice. Full-hand milking, clean dry teats, a well-maintained milking machine and a post-milking teat dip.
• Safe housing. Non-slip floors, enough space, and no sharp edges near the udder.
• Clean feed. Remove mouldy fodder and keep rodenticides away from animal areas.

Frequently asked questions

Is blood in milk after calving normal?

Mild pink or blood-tinged milk in the first few days after calving is common, especially in heifers with udder swelling, and usually clears within about a week. If it lasts longer, gets heavier, or comes with a hot quarter or fever, call your veterinarian.

Can we drink milk with blood in it?

No. Milk with visible blood should not be used for people or added to milk that is sold. Keep it separate until the milk is completely normal again, and follow any withdrawal period if your vet gives medicines.

How do I stop blood in my cow's milk?

Milk the affected quarter gently and completely, keep the cow calm on a dry floor, check for mastitis, and let post-calving bleeding settle on its own. For prevention, manage the transition period, balance minerals and vitamins, and use good milking practice. Persistent or heavy bleeding needs a veterinarian.

References: MSD Veterinary Manual — Mastitis in Cattle; literature on udder oedema and haemolactia in dairy cattle on NCBI/PMC; ICAR dairy management resources.

This article is general educational guidance and is not a substitute for veterinary care. Heavy or persistent bleeding, a hot or hard quarter, fever, or bleeding from other sites needs a qualified veterinarian.

By Cattle Remedies