By:  Alexis Thompson, Dairy Challenge Student and Donna M. Amaral-Phillips, Ph.D.             Printable Version

Contagious mastitis is a financial and herd health concern for dairy farmers. In most of the US, the common contagious mastitis pathogen isStaphylococcus aureus. Cows with contagious mastitis are able to transmit it to herdmates which can result in an increased bulk tank somatic cell count (SCC) and decrease milk production. Bulk tank SCC and decreased milk production negatively affect the milk check and often prevent bonuses. Some simple steps can prevent losses from contagious mastitis.

  • Teat dip. Post-dipping teats completely after milking to kill pathogens that are deposited on the teat skin during milking. This can reduce new infections by almost 50%. If a commercial product is used, it should have research proving its effectiveness against contagious mastitis. The National Mastitis Council maintains a summary of peer-reviewed research on teat dips (http://www.nmconline.org/docs/Teatbibl.pdf). Teat dips are commonly applied two different ways, dipping and spraying. Dipping ensures good coverage of the teat skin. Spraying is thought to use less dip than dipping but spraying should be done from under the udder. To evaluate coverage of dip, a paper towel can be wrapped around a teat then unwrapped. If there are dry areas on the paper towel, this indicated that good coverage was not achieved. Pre-dip should also be used before milking to reduce environmental infections.
  • Milk time hygiene. Strict milking procedures should be followed in the parlor. Gloves should be worn when preparing the cows for milking. Teats should be clean and dry before the milking unit is attached. Individual paper towels or wash clothes should be used per cow to prevent transfer from cow to cow during udder preparation. The number of liner slips should be reduced as this introduces bacteria into the teat canal. If liner slips are common, an alternative liner size or shape may be needed.
  • Dry Cow Therapy. An intra-mammary infusion of antibiotics given at dry off in all quarters may treat existing infections, prevent infections in the dry lot, and contain higher antibiotic concentrations without having to worry about milk withdrawals.
  • Segregation. Contagious mastitis can be spread through the herd during milking. Cows with contagious mastitis should be separated from the rest of the herd and milked last. This reduces the chance of spreading the pathogen to other members of the dairy herd.
  • Cull. Cows with chronic contagious mastitis that are not responsive to treatment should be culled. Cows that test positive for Staph. aureusshould be culled. Chronic cows can infect other cows in the herd. By culling the source of the infection, Staph. aureus can be controlled in the herd. Removing chronic cows will be immediately reflected in the lowering of bulk tank SCC.