D100
California Mastitis Test (CMT)
Introduction: The California Mastitis
Test (CMT) is a rapid, accurate, animal-side test to help determine somatic
cell counts (SCC). The term somatic cell is used to identify any cell in the body.
With the CMT test, the somatic cells that are being measured are mainly
neutrophils. Neutrophils are white blood cells that help the body fight
infection and are present in increased numbers in the udder when the animal has
mastitis. The CMT test was developed to sample individual udder halves to
determine the presence of subclinical mastitis. The test can also be conducted
on bucket and bulk tank milk samples to help determine somatic cell counts
(SCC) of the entire herd.
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How to Perform the Test: A small sample of milk (approximately
½ teaspoon) from each teat is collected into separate compartments of a plastic
paddle that has shallow cups marked A, B, C and D. An equal amount of CMT
reagent is added to the milk. The paddle is rotated to mix the contents. In
approximately 10 seconds, the score should be read, while continuing to rotate
the paddle. Because the reaction disappears within 20 seconds, the test must be
read quickly.
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How to Read the Results: The CMT reagent reacts with the
neutrophils, and the mixture thickens or gels in proportion to the amount of
cells that are present. High levels of neutrophils indicate infection. To
become accurate and consistent, practice this test on animals with a known SCC.
|
CMT Score |
Average Somatic Count
(Cells per milliliter) |
Description of reaction |
|
N
(negative) |
0-480,000 |
No thickening, homogeneous. |
|
T (trace) |
up to
640,000 |
Slight thickening. Reaction
disappears in 10 seconds. |
|
1 |
660,000 |
Distinct thickening, no gel
formation. |
|
2 |
2,400,000 |
Thickens immediately,
begins to gel, levels in the bottom of cup. |
|
3 |
>10,000,000 |
Gel is formed, surface
elevates, with a central peak above the mass |
Treatment: Refer to the mastitis information
found on page F500.