Mastitis in Cows and Buffaloes: CMT and Somatic Cell Count

Mastitis is infection and swelling of the udder, and the CMT and somatic cell count are milk tests that can help find it in cows and buffaloes. They can help detect hidden mastitis even when the milk looks normal, and a registered veterinarian reads the result together with the animal's signs and history.

What is mastitis?

Mastitis (thanaila in Hindi) means the udder is inflamed, usually because germs have entered through the teat opening. The udder has four quarters. Each quarter makes milk on its own, so one quarter can be sick while the other three look fine.

There are two kinds:

• Clinical mastitis can be seen. The udder may be hot, swollen or painful. The milk may look watery, stringy, clotted or blood-stained. Some animals also get fever and eat less.
• Subclinical mastitis cannot be seen. The udder and the milk look normal, but milk yield and milk quality are slowly falling. This hidden form is usually more common than the visible form.

Germs spread at milking time through hands, cloths and machines. They also come from wet, dirty bedding and mud, and teat injuries let them in. If mastitis goes unnoticed, the udder can be damaged for good and a quarter may stop making milk. Because hidden mastitis gives no warning, a milk test can help find it early.

How the CMT works

CMT stands for California Mastitis Test. It is done on fresh milk, one quarter at a time.

A few drops of milk from each quarter are mixed with a test liquid on a small paddle with four cups. The liquid breaks open the white blood cells in the milk, and the mixture turns thicker, like a thin jelly. The more cells there are, the thicker the jelly and the higher the score. Scores usually run from negative and trace up to 1, 2 and 3.

A high score may indicate inflammation in that quarter. A negative score suggests the quarter is probably healthy. The CMT does not name the germ. It only shows how many cells are in the milk.

Each quarter is tested on its own because a mixed sample from all four teats can hide one sick quarter. The healthy milk dilutes it.

What is the somatic cell count?

Somatic cells are the body's own cells found in milk. Most of them are white blood cells that rush to the udder to fight an infection. Healthy milk has only a small number of them.

The somatic cell count (SCC) measures how many of these cells are in the milk. A high count may indicate that the udder is inflamed or infected. It is a common way to judge udder health and milk quality.

A high count tells your vet that the udder is inflamed. It does not tell why, because inflammation can follow an infection or an injury. Counts are also naturally higher in the first days after calving and near the end of the milking period. Your vet keeps this in mind when reading the result.

How to collect a milk sample

The test needs fresh milk, quarter by quarter. Follow these steps:

• Wash and dry your hands.
• Clean the teats and dry them well.
• Throw away the first few streams of milk.
• Collect milk from each quarter into its own clean bottle.
• Label each bottle with the animal's name or tag number and the quarter: front left, front right, rear left or rear right.
• Keep the bottles cool, out of the sun, and bring them to the lab soon.

Tell the lab if the animal calved in the last few days or has had any recent medicine. In Bhopal, sample collection at your door is free. See Free Home Sample Collection in Bhopal: How It Works for the steps.

When to test and which tests go with it

Ask your vet about a milk test when:

• milk yield falls and the cause is not clear
• the milk looks normal, but a quarter feels firm or looks bigger or smaller than the others
• several animals in the herd have udder problems
• your vet advises a routine herd check

Not every fall in milk is mastitis. Fever, tick fever (a blood infection spread by ticks), feed changes and other illness can also lower milk, so your vet may look beyond the udder.

• The Mastitis Test (CMT) & Somatic Cell Count checks the milk, quarter by quarter.
• The Complete Blood Count (CBC) counts the blood cells and can help show whether the body is fighting an infection or is short of blood.
• The Mastitis Control Pack puts the milk test and the blood count together.

Reporting time is confirmed when you book. For the other farm tests, read Lab Tests Every Dairy Farmer Should Know About.

When to talk to your vet

Call your vet if you see clots, flakes, blood or watery milk, or a hot, hard or painful udder. Call at once if the animal has fever, looks dull, stops eating or gives suddenly less milk.

Also speak to your vet if one quarter dries up, if scores stay high on repeat tests, or if several animals in the herd are affected. Your vet can suggest an udder-care routine for your farm.

Test results are not a diagnosis by themselves. A registered veterinarian reads them together with the animal's signs and history, and may choose treatment or further tests.