Duration of Subclinical Mastitis Prior to Occurrence of Non-severe Clinical Mastitis — Results of a Preliminary Analysis

摘要

Clinical mastitis is a significant problem even on dairy farms with a low somatic cell count (SCC). In the U.S. the distribution of etiologies of environmental mastitis pathogens is divided among Gram negative, no-growth, and Gram-positive pathogens with each group representing about one-third of clinical cases (Ruegg, 2018). Recommendations for antimicrobial treatment vary depending on etiology, severity, parity, duration of subclinical infection preceding the clinical case and environmental factors. Research has identified that few non-severe cases that are no growth or caused by E. coli will benefit from antimicrobial therapy (Fuenzalida and Ruegg, 2019). Among Gram-positive organisms, environmental streptococci often represent the majority of the cases and antimicrobial therapy has typically been recommended (Lago et. al., 2011). In recent years, advances in diagnostic technology have shown that environmental streptococci are a heterogenous group composed of a greater variety of organisms thatpreviously identified and treatment recommendation need to be reconsidered. We are currently conducting a negatively controlled randomized clinical trial to evaluate treatment strategies for Grampositive mastitis pathogens using Matrix-assisted last desorption/ionization time-of-flight (MALDI-Tof) to differentiate among pathogens. While the larger study is on-going, the objective of this analysis using partial data from this trial was to evaluate differences in duration of subclinical mastitis prior tooccurrence of a non-severe clinical case based on etiology of the clinical case.