Mastitis in Dairy Cows: Signs, Treatment and Prevention

Quick answer

Mastitis is inflammation of the udder, almost always caused by bacteria entering through the teat. Look for clots, flakes or watery milk, and a hot, hard, swollen or painful quarter. A cow with mastitis that is also dull, off feed, feverish or down needs a vet urgently. Many infections are hidden (subclinical) and only show up on tests. Treatment should be chosen with your vet, treated milk must be discarded for the withdrawal period on the label, and clean, consistent milking prevents most cases.

How mastitis happens

Bacteria get into the udder through the teat canal, usually around milking time or while the teat end is still open after milking. Vets divide the bacteria into two broad groups.

Contagious bacteria, such as Staphylococcus aureus and Streptococcus agalactiae, live in infected udders and spread from cow to cow during milking: on the milker's hands, shared udder cloths and milking machine liners.

Environmental bacteria, such as E. coli, Klebsiella and Streptococcus uberis, live in dung, wet bedding, mud and dirty water. They infect teats when cows lie in dirty places. In many herds, most clinical cases are environmental.

Risk goes up with dirty, wet housing, poor milking hygiene, faulty milking machines, teat injuries, and the period around drying off and calving.

Signs of mastitis

Clinical mastitis

You can see something is wrong. Vets often grade it:

• Mild: abnormal milk only, such as clots, flakes, or watery or discoloured milk. The cow seems well.
• Moderate: abnormal milk plus a quarter that is swollen, hot, hard, red or painful. The cow still eats.
• Severe: the cow is ill as well, with fever, loss of appetite, dullness, a drop in milk, watery or bloody secretion, sunken eyes, shaking, diarrhoea, or going down. Severe cases, often caused by E. coli and related bacteria, can kill a cow quickly.

Subclinical mastitis

The milk and udder look normal, but the quarter is infected. Yield drops and somatic cell count (SCC) rises. These cows are a reservoir of infection for the rest of the herd. You only find them by testing.

How to check

Strip the foremilk from each teat into a strip cup or onto a dark surface before every milking. This is the easiest way to catch clinical cases early.

Feel the udder after milking for heat, hardness, lumps or one quarter much bigger than the others.

The California Mastitis Test (CMT) is a simple, cheap cow-side paddle test. Milk from each quarter is mixed with a reagent; the more it thickens or gels, the higher the cell count and the likelier an infection.

Somatic cell counts from individual cows or the bulk tank show how much hidden mastitis is in the herd. An individual cow SCC of about 200,000 cells/mL or more suggests a likely infection, and lower bulk tank counts generally mean a healthier herd.

Milk culture sent to a lab tells you which bacteria are involved, which helps your vet choose the right treatment and plan prevention.

Treatment

Treatment depends on how severe the case is and what's causing it, so talk to your vet before reaching for a tube.

• Mild and moderate cases are often treated with an intramammary tube into the affected quarter. Some mild cases may not need antibiotics, which is something a vet decides, often using culture results.
• Severe cases need a vet urgently. Treatment usually focuses on supportive care such as fluids and anti-inflammatory drugs, plus antibiotics where the vet thinks they're needed.
• Frequent stripping of the affected quarter may be advised to remove infected milk and toxins.
• Chronic cases that keep flaring up, especially with Staph. aureus, respond poorly. Vets may suggest drying off the quarter or culling the cow to protect the rest of the herd.

Use only products your vet recommends, follow the dosing and course exactly, and keep records of every treatment.

Milk withdrawal

Milk from treated cows contains drug residues and must not go into the milk you sell or drink. Discard it for the full milk withdrawal period. Withdrawal times differ between products and how they're used, so follow the product label and your vet. Mark treated cows clearly, with a leg band or paint, and milk them last.

Prevention

Most mastitis is prevented by doing simple things consistently.

At every milking:

• Milk in a clean, calm place with clean hands, ideally wearing gloves
• Strip foremilk and check it
• Clean and dry teats before milking, using a separate clean cloth or paper towel for each cow
• Milk gently and completely; don't overmilk with a machine
• Dip or spray teats after milking with an effective teat disinfectant, covering the whole teat. This is one of the most effective ways to stop contagious mastitis.
• Milk infected and treated cows last, or with a separate unit

Housing and hygiene:

• Keep bedding clean and dry and lying areas free of dung and mud
• Offer fresh feed after milking so cows stand while the teat canal closes
• Keep wallows, yards and walkways as clean and dry as possible

Herd management:

• Service milking machines regularly, and replace liners as recommended
• Plan dry-off with your vet. Dry cow therapy (blanket or selective) and internal teat sealants help cure existing infections and prevent new ones during the dry period
• Test new cows before they join the herd
• Cull chronically infected cows that don't respond
• Ask your vet whether vaccines are useful in your herd; some reduce the severity of certain types of mastitis

When to see a vet

Call a vet urgently if a cow with mastitis:

• is dull, off feed, shaking, or has a fever
• has a very swollen, hard, cold or blue-black quarter (possible gangrenous mastitis)
• produces watery, yellow, bloody or foul-smelling secretion
• is dehydrated, has diarrhoea, or is down and can't get up

Also call your vet if:

• you're seeing frequent cases, or several cows at once
• a case doesn't improve with the treatment advised
• your bulk tank somatic cell count is rising
• you'd like a mastitis control plan or milk cultures done

In Pakistan

Mastitis is one of the most common and costly problems on dairy farms in Pakistan, in buffaloes as well as cows. Hand milking with wet hands, one cloth shared between animals, dirty floors and muddy wallows all spread infection. Simple habits such as dry hands, a clean cloth per animal, teat dipping, clean floors and keeping animals standing after milking make a real difference. Ask your local veterinary hospital about CMT testing and milk culture. The same principles apply to the Nili-Ravi buffalo and to breeds like the Sahiwal.

When adding cows or buffaloes to your herd, check udders and milk carefully and buy from verified sellers on Paalo.