Comparative Efficacy of Antimicrobial Practices in Small vs. Large Animal Practice

Thesis Abstract

Antimicrobial use in veterinary medicine is acknowledged as a pivotal factor in shaping antimicrobial resistance trends, yet practices and outcomes may differ markedly between small-animal and large-animal contexts due to diverse patient populations, disease profiles, and stewardship infrastructures. This study addresses the problem of inconsistent antimicrobial stewardship between small- and large-animal practices and its implications for treatment efficacy, resistance selection, and economic impact on clients and clinics. The aim is to compare the efficacy of antimicrobial practices across these practice types and identify actionable determinants of optimal outcomes. Specific objectives are (1) to quantify antimicrobial prescription patterns, compliance with guidelines, and duration of therapy in small- vs. large-animal clinics; (2) to evaluate clinical outcomes including treatment success rate, relapse, and adverse events; (3) to assess antimicrobial resistance trends in contemporaneous isolates from treated cases; (4) to identify contextual factors (training, access to diagnostics, client expectations) influencing stewardship decisions; and (5) to develop a framework for harmonizing best practices across practice types. A cross-sectional comparative design will be employed, nested within a prospective cohort component for outcome tracking. The population comprises registered veterinarians and their caseloads in 60 clinics (30 small-animal and 30 large-animal) across five regions with established diagnostic laboratories. A stratified random sampling approach will yield 300 veterinarian respondents and 1,800 patient cases (900 small-animal and 900 large-animal) over a 12-month period. Data collection will combine structured veterinarian surveys, patient record audits, and laboratory data from partner diagnostic centers. Instruments include a validated antimicrobial stewardship questionnaire, a case-level data abstraction form capturing diagnosis, treatment regimens, duration, de-escalation practices, and outcome indicators, and a microbiology reporting template. Instrument validity will be established through expert panel review and pilot testing (n=20). Reliability will be assessed with Cronbach’s alpha for the survey (target ?0.80) and inter-rater agreement (Cohen’s kappa ?0.70) for record abstractions. Data analysis will proceed in stages. Descriptive statistics will summarize prescription patterns, duration, and outcome frequencies by practice type. Inferential analyses will include multivariable logistic regression to identify predictors of treatment success and relapse, controlling for species, ailment category, and severity. Generalized linear mixed models will account for clustering at clinic and region levels. Differences in guideline adherence and de-escalation rates will be tested using chi-squared tests and ANOVA where appropriate. Time-to-event analyses (Kaplan-Meier) will examine relapse-free survival. Microbiological data will be analyzed to track resistance trends via proportion tests and logistic regression linking stewardship practices to resistance outcomes. A theoretical framework combining the Theory of Planned Behavior and the Diffusion of Innovations will be used to interpret determinants of stewardship behavior, with thematic analysis of interview data (if conducted) to triangulate quantitative findings. Expected findings include higher guideline-concordant prescribing in small-animal clinics due to routine diagnostic workflows, and greater reliance on broad-spectrum agents in large-animal practices driven by field constraints. It is anticipated that de-escalation and targeted therapy will correlate with higher clinical success and lower relapse rates, while clinics with rapid diagnostic access will demonstrate improved outcomes and reduced resistance indicators. The study will contribute to knowledge by quantifying cross-practice differences, identifying modifiable factors underpinning antimicrobial stewardship, and proposing a harmonized framework for cross-setting best practices. The study will advance the understanding of how antimicrobial practices influence treatment efficacy and resistance dynamics in veterinary medicine, offering evidence-based recommendations for policy makers, veterinary associations, and practitioners. It will advocate for standardized stewardship metrics, enhanced access to diagnostics, and targeted continuing education to bridge gaps between small- and large-animal practices. The main conclusion is that harmonizing stewardship practices across practice types, with emphasis on timely de-escalation, diagnostic-supported decisions, and adherence to guidelines, will improve treatment outcomes and mitigate resistance emergence. Recommendations include development of cross-sector stewardship guidelines, investment in rapid diagnostic capabilities, regionally tailored continuing education, and routine monitoring of prescription patterns and resistance trends.