Mastitis (thanaila)
It rarely kills, but no other disease drains a dairy quietly like mastitis — discarded milk, a permanently blind quarter, higher culling, and a bulk tank that fails the somatic-cell count.
- Cause
- Bacteria up the teat canal
- Costliest form
- Sub-clinical (hidden)
- Main risk window
- First days after calving
- Best control
- Clean, dry bedding + teat dip
Overview
Mastitis is inflammation of the udder, almost always because bacteria have travelled up the teat canal and multiplied in the milk-producing tissue. The bacteria come from a dirty environment — wet, dung-caked bedding and standing water — or are carried from an infected quarter to a healthy one on milkers’ hands, cloths and the milking machine.
It shows in three grades. Sub-clinical: milk and udder look normal but the cell count is high and yield is quietly down — only a test finds it, and this is where most of the money is lost. Clinical: visible clots, flakes or watery milk, with or without a swollen, hot, painful quarter. Severe (peracute): the quarter is hard and cold, the milk is like bloody water, and the cow is off feed, feverish and may die — E. coli mastitis just after calving is the classic example.
Treatment is intra-mammary antibiotic tubes and, for sick animals, systemic treatment by a vet — but cure rates for established infections are poor, especially Staph aureus. The return is in prevention: a clean, dry place to lie, a clean milking routine, full milk-out, teat dipping, and drying cows off properly.
This is a general guide, not a substitute for a veterinarian. Always call a vet for diagnosis, dosage and treatment of a sick animal.
Signs and how to check
- Draw the first few streams from each teat onto a dark strip cup or black tile before every milking — look for clots, flakes, or watery, discoloured milk.
- Feel each quarter: mastitis makes it swollen, hard, hot and painful, and the quarters become uneven in size.
- A sudden drop in a cow’s yield, or milk that will not thicken curd properly, points to hidden (sub-clinical) mastitis.
- For herd screening, use the California Mastitis Test (CMT) paddle — a gel reaction shows a high cell count quarter by quarter.
- Severe cases: watery blood-tinged secretion, a cold hard quarter, fever, no appetite, and a very dull cow — an emergency.
Why cows get mastitis
- Wet, dirty bedding and muddy, dung-fouled standing areas — the number-one source of infection.
- Milking with dirty hands, a common udder cloth, or an ill-maintained milking machine that carries bacteria cow to cow.
- Not milking the udder out completely, or stopping milk suddenly without a proper dry-off.
- Teat injuries, teat-end damage from over-milking, and biting flies around the udder.
- The stress and immune dip around calving; older cows and cows with a past attack are more prone.
Clean-milking routine
- Wash your hands; wash visibly dirty udders with clean water and dry each teat with an individual paper or cloth towel — never a shared wet cloth.
- Foremilk-strip each teat onto a strip cup and check before you start.
- Milk fully and quickly; avoid dry, rough hand-milking and machine over-milking.
- Dip or spray every teat in an antiseptic teat dip immediately after milking, every milking.
- Milk known-infected cows last, and keep their utensils separate.
- Keep cows standing and eating for 30 minutes after milking so the teat canal closes before they lie down.
Treatment and dry-cow care
- Treat clinical cases early with the full course of an intra-mammary antibiotic tube after fully stripping the quarter; a vet adds injectable antibiotics and anti-inflammatory for sick cows.
- Discard milk from treated quarters and observe the full milk-withdrawal period before the milk goes to sale or the household — this is non-negotiable.
- At the end of lactation, dry the cow off abruptly (stop milking completely) and infuse a long-acting dry-cow antibiotic in every quarter on veterinary advice — the dry period is the best time to cure and to prevent new infections.
- A quarter that stays hard and yields watery or no milk after treatment is "blind" — cull for it or manage the cow on three quarters; keep milking it out to reduce spread.
- Cull cows with repeated clinical attacks or chronic high cell counts — they are the reservoir that keeps infecting the herd.
Animals affected
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Frequently asked questions
Can I drink or sell milk from a cow being treated for mastitis?
No. Milk from a treated quarter — and usually the whole udder — must be thrown away for the full withdrawal period printed on the antibiotic tube (commonly 48–96 hours after the last dose, longer for some products). Antibiotic residue in milk is a serious food-safety problem and also ruins curd and paneer setting.
The milk looks fine but yield dropped. Could it still be mastitis?
Yes — that is sub-clinical mastitis, and it is the most expensive kind because it goes unnoticed. Use a CMT paddle or get a somatic-cell count. A single high-cell cow can also pull up the whole bulk-tank count and fail a dairy’s quality test.
One teat has gone hard and gives only watery milk. Will it recover?
If a quarter stays hard and abnormal after a full treatment course, the milk-producing tissue is usually scarred and that quarter is "blind" for good. Keep stripping it out to limit bacteria spreading to the other quarters, and decide whether to run the cow on three quarters or cull, based on her overall yield.
What is the single most effective thing I can do to reduce mastitis?
Give every cow a clean, dry place to lie down. Most infections are picked up between milkings from wet, dung-soiled bedding. Dry bedding, good drainage, plus teat-dipping after every milking, will cut new cases more than any medicine.
Signs, prevention and treatment follow ICAR, DAHD and state veterinary-university practice; vaccine schedules are the commonly notified ones and may vary by region or outbreak status. Always confirm with a veterinarian before treating an animal. editorial policy.