Strep. Non-Ag Mastitis

Where Do They Live?

Bedding, soil or water that is contaminated by manure.

How Is Infection Spread?

From the environment to the cow at any time. The risk of new infection is highest in the first two weeks of the dry period and around calving time.


About 50% of cases will be clinical during the course of infection. About 60% last less than 30 days.


Clinical signs (changes in milk, udder or sick cow). Culture of milk samples collected at the beginning of clinical signs.


Reduced production, loss of milk discarded for treatment and withdrawal time. Some infected cows become sick (fever, off feed).


Sensitive to penicillin, but cost-recovery on routine usage is controversial and variable. Resistance to antibiotics (Strep. uberis) has been reported, but is very rare.

Estimated Cure Rates:

Antibiotic treatment during lactation - 70-100%
Antibiotic treatment at dry-off time - 70-100%

Preventive Measures:

  • Milk only clean, dry teats.
  • Keep bedding clean and dry in lactating and dry cow environments.
  • Calve cows in a clean, dry box stall or on pasture.
  • Keep yards, pastures, and laneways dry.
  • Maintain equipment to reduce liner slips and keep teat ends healthy.
  • Balance lactating and dry cow rations to meet NRC recommendations.

For more information:
Toll Free: 1-877-424-1300
Author: Ann Godkin - Veterinary Scientist, Cattle/OMAFRA; Doug Dulmage - Dairy Farmers of Ontario; Mark McDougall - Dairy Farmers of Ontario
Creation Date: 12 January 1998
Last Reviewed: 12 January 1998