Veterinary Antimicrobial Use and Food-Safety Implications Among Food-Producing Animals in Sokoto, Nigeria: A Three-Year Retrospective Study

Abstract

Background: Antimicrobial use (AMU) in food-producing animals is a recognised driver of antimicrobial resistance (AMR) selection under the One Health framework, and when medicines are used close to slaughter or without withdrawal-period compliance, it’s a direct contributor to antimicrobial residues in foods of animal origin. Residues and resistant foodborne pathogens both represent tangible consumer-protection hazards distinct from, though related to, the resistance-selection concern that dominates most veterinary AMU literature. This study assessed patterns and temporal trends of AMU among food-producing animals at a multi-species veterinary clinic in Sokoto, Nigeria, between 2021 and 2023, with particular attention to the food-safety implications of the observed prescribing pattern. Methods: A retrospective analysis was conducted using timestamped clinical records for avian, bovine, caprine, and ovine cases documented between January 2021 and December 2023. AMU was defined as documentation of at least one antimicrobial agent in a clinical case record. Antimicrobial agents were standardised by generic name, grouped into pharmacological classes, and further mapped, exploratorily, to the WHO Access, Watch, Reserve (AWaRe) framework. Differences in AMU and antimicrobial class distribution across years and species were evaluated using Pearson's chi-square tests of independence, with Cramér's V as effect size; all statistics were computed specifically on the four-species food-producing subset. Results: A total of 14,252 food-producing animal clinical cases were recorded, comprising 7,014 ovine (49.2%), 4,736 caprine (33.2%), 2,214 avian (15.5%), and 288 bovine (2.0%) cases. Antimicrobials were documented in 12,169 cases (85.4%), rising from 84.2% in 2021 to 87.0% in 2022 and 86.2% in 2023 (χ² = 15.32, df = 2, p < 0.001; Cramér's V = 0.033). AMU varied significantly by species (χ² = 298.05, df = 3, p < 0.001; Cramér's V = 0.145). Oxytetracycline was the most frequently documented antimicrobial (5,387 of 14,367 entries; 37.5%), a compound independently confirmed to exceed regulatory maximum residue limits (MRLs) in Nigerian beef, poultry, and fish in multiple prior residue-testing studies. Tetracyclines constituted the largest antimicrobial class (41.2%), and antimicrobial class distribution differed significantly by year (χ² = 542.53, df = 20, p < 0.001) and species (χ² = 1894.72, df = 30, p < 0.001; Cramér's V = 0.210). Exploratory AWaRe classification indicated 84.1% Access-category and 15.9% Watch-category entries, with Watch use highest in avian cases (22.3%), a species in which enrofloxacin and tylosin, both documented above MRLs in independent Nigerian poultry-residue analyses, were disproportionately represented. Conclusion: The prescribing pattern documented at this clinic, dominated by tetracyclines and administered without recorded withdrawal-period guidance or residue testing, aligns closely with the antimicrobial classes independently confirmed to exceed maximum residue limits in Nigerian meat, milk, and poultry products in the published residue-surveillance literature. This convergence between prescribing volume and documented residue risk supports treating veterinary antimicrobial stewardship and food-safety residue surveillance as a single, linked priority for food-producing animal practice in Sokoto State, rather than as separate concerns.