A case-case-control study of cefovecin use and third-generation cephalosporin-resistant Escherichia coli infections in cats

Objective To determine if cefovecin administration increased the risk of third-generation cephalosporin (3GC)–resistant Escherichia coli infections in cats. Methods In this retrospective case-case-control study, cases were cats with 3GC-susceptible or 3GC-resistant E coli infections at the Cornell University Hospital for Animals from 2009 to 2023; controls were randomly selected from all feline patients seen during the study period. Exposure data were collected via review of medical records. Direct acyclic graph–driven multivariable regression models of each potential exposure were built for each case-control grouping. Results 36 susceptible cases (3% cefovecin treated), 14 resistant cases (21% cefovecin treated), and 72 controls (6% cefovecin treated) were identified. Resistant cases had a higher proportion of cefovecin use (21%) than susceptible cases (3%) and controls (6%), but case numbers were too low to evaluate whether cefovecin use was associated with either infection type. Most of the cats that received cefovecin (75%) were underdosed. The overall frequency of cefovecin administration was low (7%) compared to previous studies. Conclusions Cefovecin use was less frequent than previously reported, resulting in too few cases to determine whether cefovecin use is associated with 3GC-resistant E coli infections in cats. Clinical Relevance The sample size was too small to evaluate association between cefovecin and 3CG resistance. Based on prudent antimicrobial stewardship, veterinarians should limit cefovecin use to cases where oral antimicrobial treatment is impossible and, ideally, its use is supported by antimicrobial susceptibility testing to avoid selecting for antimicrobial resistance in treated cats. When using cefovecin, veterinarians should ensure they are administering the label-recommended 8-mg/kg dose.