Antimicrobials for Dog Bite Wounds in Dogs

Joshua B. Daniels, DVM, PhD, DACVM, Colorado State University

ArticleLast Updated May 20233 min read
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In the Literature

Kalnins NJ, Gibson JS, Stewart AJ, et al. Antimicrobials in dog-to-dog bite wounds: a retrospective study of 1526 dog bite events (1999-2019). J Vet Intern Med. 2022;36(6):2028-2041. doi:10.1111/jvim.16574 

The Research … 

Dogs with bite wounds from other dogs are commonly presented in companion animal practice, but use of culture and susceptibility testing and antimicrobial agents varies.  

This retrospective study evaluated medical records of 1,436 dogs with dog bite wounds presented to 3 Australian university clinics over 10 years to assess the most commonly prescribed antimicrobials and frequency of culture and susceptibility testing. The authors categorized antimicrobial prescriptions by importance (as defined by a national antimicrobial resistance advisory group) and evaluated frequency of prescribing less than the recommended dosage as well as whether antimicrobial choice was associated with differences in wound severity, clinic, and year. 

Most dogs (88.1%) were administered at least one antimicrobial on presentation, most commonly amoxicillin/clavulanate (medium importance), followed by first-generation cephalosporins (medium importance). Enrofloxacin (high importance) was administered to 7.6% of dogs, typically as part of a multiagent therapy regimen. Cefovecin (high importance), a third-generation cephalosporin, was administered to 0.8% of dogs. Use of a high-importance antimicrobial was significantly associated with wound severity grade, clinic, and year (enrofloxacin and cefovecin became available within the study time frame). Prescribing less than the recommended dosage was common, occurring with 13.4% of amoxicillin/clavulanate, 26.1% of cephalexin, 11.1% of enrofloxacin, and 7.7% of cefovecin prescriptions. 

Culture and susceptibility testing was performed in 1.8% of cases; most had grade 4 or 5 wounds. Aerobic growth consisted of bacteria that typically reside in the oropharynx. Whether samples were taken at the time of patient presentation or following deterioration in clinical status was unknown. 

Outcome data were limited because of the nature of the study, but 86.9% of a subset of 323 dogs had no complications. Prescribing less than the recommended dosage occurred in 26.2% of dogs with complications and 25.4% of dogs without complications.

… The Takeaways 

Key pearls to put into practice: 

  • The frequent prescribing of less than the recommended dosage observed in this study should prompt re-evaluation of dosages in clinic formularies as well as dosage form selection when calculated doses for patients fall between available dosage sizes (eg, amoxicillin/clavulanate 250 mg vs 375 mg).  

  • Deciding which wounds are appropriate to culture can be challenging. The number of patients in this study was insufficient to determine an association between wound score and complication rate; however, the gap between the proportion of wounds cultured and those that developed complications was substantial, and some dogs may have benefited from targeted rather than empirical therapy. 

  • Culture for wounds can be misused. Wounds with no evidence of infection should not be sampled because bacteria are present in noninfected wounds and largely do not represent organisms cultivated from clinically infected wounds. Some laboratories perform culture and susceptibility testing and report everything grown in the culture, regardless of clinical relevance. This may lead to unnecessary use of antimicrobials, as multidrug-resistant but clinically insignificant organisms can be isolated from cultures.