Effect of extended cefquinome treatment on clinical persistence or recurrence of environmental clinical mastitis.

The effectiveness of antibiotic treatment of clinical mastitis (CM) is classically evaluated using bacteriological cure, which provides a concise and objective way of assessing efficacy but does not reflect the situation in the field where persistence or recurrence of clinical signs lead to perceived treatment failure. If clinical signs persist or recur, intramammary (IMM) treatment is often extended or supplemented with parenteral therapy in the expectation of a more efficient elimination of clinical signs or a lower probability of recurrence. The objective of this study was to evaluate the efficacy against clinical persistence or recurrence of three cefquinome treatment regimes, standard 1.5-day intramammary (SIMM), 5-day extended intramammary (EIMM) and combination of EIMM plus 5-day extended parenteral (ECOMBO) treatment. The study was conducted on three dairy farms with a high recurrence rate of environmental mastitis. Efficacy was evaluated using a multi-level model at the quarter and at the cow level, based on the persistence or recurrence of clinical signs at any time during a 105-day period following the end of the initial treatment, independent of pathogen. The most prevalent pathogens were E. coli (16.9%) and S. uberis (11.97%). EIMM and ECOMBO significantly decreased the persistence or recurrence of CM by 8% and 6% at the quarter level and by 9% and 8% at the cow level, respectively. ECOMBO may not reduce the persistence or recurrence of CM beyond EIMM. Whilst extended treatment regimens offered an improved outcome in this study, the producer and practitioner need to carefully consider such regimens from the perspective of prudent antibiotic use.