Corynebacterium bovis: A Practical Summary for Controlling Mastitis

Corynebacterium bovis is a contagious, Gram-positive mastitis-causing pathogen. C. bovis will typically produce little to no growth on blood agar after 24 hours of culture, but it will show creamy, gray, or white nonhemolytic colonies at 48 hours. C. bovis is mildly pathogenic and will usually cause only a mild increase in somatic cell count and a slight reduction in milk production. Information in this publication was summarized from the National Mastitis Council’s Laboratory Handbook on Bovine Mastitis (Hogan et al. 1999).

Where are these organisms found?

C. bovis will colonize the teat canal; thus, the teat canal, as well as the infected udders, will act as reservoirs for infection.

How does C. bovis spread to the mammary gland?

This pathogen is contagious and will therefore spread from cow to cow at milking.

How can you prevent and control mastitis caused by C. bovis?

Proper milking procedures, including the use of effective post-milking teat disinfectants, will help to reduce the number of new infections. After unit detachment, the application of a proven post-milking teat disinfectant should be applied with coverage over at least two-thirds of the teat barrel. The exception to this is post-dips with the active ingredient linear dodecylbenzene sulfonic acid, which are not effective against C. bovis. Dry cow therapy is very effective in eliminating this pathogen.

When are C. bovis mastitis infections most likely to occur?

New infections can occur at any time during lactation. Prevalence of C. bovis is very low in herds utilizing an efficacious post-dip.

How likely are C. bovis-infected quarters to be cured?

Dry cow therapy is very effective in eliminating C. bovis. Antibiotic therapy during lactation is not recommended. It is recommended to consult your herd veterinarian prior to starting any treatment.

Quick Notes

• C. bovis is a contagious pathogen that colonizes the teat canal.
• Effective post-milking disinfectants will dramatically reduce the C. bovis infection rate.
• Dry cow therapy is very effective in eliminating C. bovis.

References

Hogan, J. S., R. N. Gonzalez, R. J. Harmon, S. C. Nickerson, S. P. Oliver, J. W. Pankey, and K. L. Smith. (1999). Laboratory Handbook on Bovine Mastitis. Madison, WI: National Mastitis Council.