Anti-inflammatory therapy in acute endotoxin-induced bovine mastitis.

Acute mastitis was induced in lactating cows by intramammary challenge with 10 micrograms of Escherichia coli lipopolysaccharide. The cows were monitored clinically prior to and for 96 hours after challenge. Milk production, complete blood counts, serum enzyme activities and milk indicators of inflammation were evaluated. Endotoxin challenge was in 7 groups of 3 cows each. Within the groups, cows were randomly assigned to 3 intravenous treatments: saline controls, steroid (one dose of dexamethasone at 0.44 mg/kg) and non-steroidal agent (two doses of flunixin meglumine at 1.1 mg/kg, 8 h apart). Anti-inflammatory therapy reduced rectal and mammary gland surface temperatures. Milk production was significantly reduced (p less than 0.05) in cows treated with dexamethasone. Although dexamethasone treatment produced significant increases (p less than 0.05) in blood leukocytes and segmented neutrophils, milk somatic cell concentrations were not significantly altered. Flunixin meglumine did not alter milk production or blood or milk leukocytes.