Currently robbing the U.S. dairy industry of $1.7 billion a year, mastitis can be debilitating to a dairy operation because of decreased milk production and increased chronic health problems.1, 2

“With demand for higher milk quality standards increasing, dairy producers need to implement measures to prevent, control and treat mastitis,” says Jerry Olson, DVM, MS, Pfizer Animal Health. “Such measures should include identifying both clinical and subclinical mastitis and instituting efficient protocols for effective treatment.”

Effects of clinical and subclinical mastitis
Three studies (Frago 2004, Kelton 2001 and Shrick 2001) have shown 8-15% higher conception rates for animals not affected by mastitis in comparison to those experiencing clinical cases. Uninfected animals became pregnant faster with approximately 19 to 25 fewer days open.3,4,5

“Reduced milk quality, decreased reproductive performance, extra labor, increased replacement cow costs, veterinary fees and treatment costs all reinforce the importance of implementing a control plan, regardless of a cooperative bonus plan,” Olson says. “Not only can mastitis impact a cow’s milk production, but also her reproductive performance.”

A good control practice for avoiding devastating effects on any dairy is to categorize clinical mastitis events by their level of visual severity – mild, medium or severe.

  • Mild mastitis is visually recognizable by the appearance of a few flakes and clots, which may not be caught in herds that do not fore-strip.
  • Medium mastitis displays flakes and clots in the milk, which are indications of inflammation of the udder, an infected swollen quarter or possible redness and disparity in comparison to the matching quarter.
  • Severe mastitis is recognized through abnormalities in the milk, indications of inflamed glands and systemic signs of the cow being ill. These cows may be off-feed, lethargic or appear to be lame because of the swollen quarter.

Unlike clinical mastitis, subclinical mastitis must be determined through testing and culture sampling. Depending on the situation, the producer may be testing cows individually through the National Dairy Herd Information Association (DHIA) or monitoring bulk tank somatic cell counts (SCC) to identify overall herd SCC changes. With individual SCC scores, a strong correlation exists between the linear score and the amount of milk lost due to mastitis.

Tips to Avoid Mastitis in the Herd
Along with the ability to identify clinical and subclinical mastitis, producers should practice tips for preventing mastitis in herds. The National Mastitis Council has developed a five-point program for producers to implement as standard protocol on all dairies. This includes post-milking teat disinfection, total dry cow therapy, therapy of clinical cases during lactation, proper maintenance of the milking machines and culling chronic problem cows.

“Maintaining a clean environment is important in limiting mastitis infections,” said Francisco Rivas, quality milk manager, Pfizer Animal Health. “Producers can treat all they want, but the infection rate will remain high unless the cow environment is less hospitable to mastitis pathogens.” Things such as composting manure and utilizing a proper milking routine can go a long way in lowering incidence rates.

In addition, record keeping and a solid protocol are two tools a producer should utilize in the fight against mastitis. Computer programs designed to help track events such as mastitis will help producers track infected cows and the frequency of infection. “Producers can benchmark their subclinical infection rate and set a goal through proper protocols to bring that number down,” Rivas said. “Even dropping the incidence rate a few percentage points can pay dividends.”

Although these initial points are very effective, additional tools are available to producers such as vaccination with J-5 vaccines and prevention programs including internal teat sealants. “Instituting an on-farm protocol will help with the treatment of mastitis also,” says Olson. “Protocols should be developed by both the producer and veterinarian to help define how to reach a diagnosis, as well as provide a treatment protocol that automatically kicks in after diagnosis.”

1Ott SL, Novak PR. Association of herd productivity and bulk-tank somatic cell counts in US dairy herds in 1996. JAVMA 2001;218(8).
2Fetrow J, Stewart S, Eicker S, Farnsworth R, Bey R. Mastitis: An economic consideration, in Proceedings. Annu Meet Nat Mast Coun 2000.
3Frago F, Ahmadzadeh A, Shafii B, Dalton JC, McGuire MA, Price WJ. Effect of Clinical Mastitis and Other Diseases on Reproductive Performance of Holstein Cows. J. Dairy Sci. Vol 87, Sppl. 1. 2004:258  
4Kelton D, Petersson C, Leslie K, Hansen D. Associations Between Clinical Mastitis and Pregnancy on Ontario Dairy Farms. Proceedings. 2nd International Symposium on Mastitis and Milk Quality 2001;200-202.
5Schrick FN, Hockett ME, Saxton AM, Lewis MJ, Dowlen HH, Oliver SP. Influence of Subclinical Mastitis During Early Lactation on Reproductive Parameters. Journal of Dairy Science 2001;84:1407-1412.