Prevention and Pirlimycin Therapy Strategies for a High Somatic Cell Count Herd: A Case Study

Objective of this field investigation was to: 1) examine the etiology and mastitis infection dynamics in a 45 cow herd and evaluate the efficacy of recommended and extended therapy (S. aureus only) with pirlimycin hydrochloride (Pirsue, Pharmacia/Upjohn Co. Kalamazoo, MI). for gram positive intramammary infections (IMI) . Percentages of cows (quarters) infected with Strep. agalactiae, Strep. dysgalactiae, and Staph. aureus were 15(5); 54(23); 46(24); respectively. Cow and quarter cure rates were: Strep.ag.-100, 100; Strep. dysgalactiae- 77, 86; Staph. aureus- 74, 85%. High cure rates were seen for all organisms possibly due to bacterial strains involved or the limited antibiotic therapy seen in this herd over the previous 10 years. Observations at the final herd visit showed significantly improved teat end health and low new infection rate due to adoption of immediate proposed strategies. Herd SCC was down to 256,000 cells/ml within 1 month post treatment and continued to be 250-350,000 cells/ml12 months later. Targeting prevention and therapy strategies based on causative organisms, and having a monitoring system in place can result in sustained lower SCC and improved milk quality and farm profitability. The objectives of this field investigation were to: 1) examine the etiology and mastitis infection dynamics in a 45 cow herd during the fall-winter whose normal herd bulk tank SCC was 500,000 cells/ml but had jumped to 1 million for 3 months; 2) investigate herd management and procedures and develop and prioritize necessary changes for mastitis prevention; and 3) evaluate the efficacy of recommended and extended therapy with pirlimycin hydrochloride (Pirsue, Pharmacia/Upjohn Co. Kalamazoo, MI). for gram positive intramammary infections (IMI)