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What is Subclinical Mastitis?


Mastitis is the most prevalent and costly disease that affects dairy cows. Producers have been struggling to corner the disease for years, but it continues to be the single largest obstacle for the dairy industry. The ability to detect mastitis early and do something about it can have a significant impact on milk production, milk quality and herd health.

When microorganisms invade a dairy cow’s udder this triggers an immune response that results in mastitis, an inflammation of the cow’s mammary gland. Mastitis-causing pathogens can be contagious, spreading from cow to cow, or environmental, coming from dirty or wet conditions in the cow’s living area.

Clinical mastitis infections are those with symptoms like udder swelling or redness that are visible to the naked eye. On the other hand, subclinical mastitis infections don’t cause any visible changes in milk or udder appearance, making it difficult to detect.

Subclinical mastitis infections affect the dairy producer’s bottom line by reducing milk production, decreasing milk quality, and suppressing reproductive performance. Cows with a high Somatic Cell Count (SCC) indicative of subclinical mastitis on the first milk test have an estimated loss in milk production of more than 1,500 pounds per cow.  


Subclinical mastitis also jeopardizes milk quality, preventing dairy producers from getting those valuable SCC premiums. In addition, it has been shown to increase the number of days open, meaning that producers will have to pay for additional services.

Research presented at the 2015 National Mastitis Council Annual Meeting concluded the cost of subclinical mastitis often is greater than that of clinical mastitis.   With an estimated cost to the U. S. dairy industry of more than $1 billion per year,   subclinical mastitis is a disease that shouldn’t simply be accepted or ignored by dairy producers. AAD is helping to address the issue with QScout MLD, which accurately diagnoses subclinical mastitis on-farm. QScout MLD utilizes a white blood cell differential to detect udder infections before visible symptoms occur, allowing dairy producers to take action and prevent losses.

1Kirkpatrick MA, Olson JD. Somatic Cell Counts at First Test: More than a Number, in Proceedings. NMC Annu Meet 2015;53-56.

2Ott, S. Costs of herd-level production losses associated with subclinical mastitis in US Dairy Cows. 1999. PP 152-156 in Proceedings of the 38th annual meeting of National Mastitis Council, Arlington VA. Natl. Mast Coun. Madison WI.



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