Mastitis therapy for cows elevated somatic cell counts or clinical mastitis.

Intramammary treatment with a broad spectrum antibiotic was evaluated for cows treated after a single high monthly somatic cell count of for cows with clinical mastitis. Forty-three quarters of 36 cows were treated after a high somatic cell count, and 56 quarters of 48 cows were treated after clinical symptoms. There was no significant decrease of cell count in response to treatment in the high somatic cell group. Organisms were isolated from 70% of the pretreatment quarter samples, but only 13% of the isolates were major pathogens. Bacteriological cure rate for major and minor pathogens combined was 23.3%. Treatment costs (antibiotics and discarded milk) were $38.19 per animal treated. Organisms were isolated from 70% of the pretreatment quarter samples of the clinical group. Forty-nine percent of the isolates were major pathogens. Bucket and quarter somatic cell counts decreased following treatment. Production rose posttreatment almost back to normal. Bacteriological cure rate was 21.6% for major and minor pathogens combined with 37% of the cured quarters becoming reinfected with minor pathogens during the monitoring period. The predominant minor pathogens isolated micrococci and coagulase negative staphylococci. The predominant major pathogens were Streptococcus uberis and coliforms.