A quantitative swab is a good non-invasive alternative to a quantitative biopsy for quantifying bacterial load in wounds healing by second intention in horses

There was a significant, high correlation (P < 0.001; r = 0.747) between the outcome of the quantitative swabs and the quantitative biopsies. The semi-quantitative swabs showed a significant, moderate correlation with the quantitative biopsies (P < 0.001; ρ = 0.524). Higher white blood cell counts for cytology were significantly associated with lower log10 colony-forming units (CFU) in the wounds (P = 0.02). Wounds with black granulation tissue showed significantly higher log10 CFU (P = 0.003). Specimens with biofilms did not yield higher bacteriological counts after a vortex and sonication protocol was performed to release bacteria from the biofilm. Based on these findings, a quantitative swab is an acceptable non-invasive alternative to a quantitative biopsy for quantifying bacterial load in equine wounds healing by second intention.