Active vs. passive surveillance, the 30-day timeline, surveillance terms, and the 'surveillance effect.'
Surveillance is a quality-improvement function, not bureaucracy. The choice between active and passive surveillance determines whether your SSI rate is signal or noise.
Routine reporting of SSI cases using data the veterinary team recorded for other reasons — clinical treatment, prescriptions, billing — with no special additional effort to identify cases.
Low effort, low sensitivity. It under-detects, because a wound that was never noted as infected is silently assumed to be fine.
Active contact with or observation of the patient, with deliberate follow-up by the veterinary provider, specifically to identify SSI cases and other surgical outcomes.
The consensus recommends active surveillance wherever possible. It is the only way to record both infected AND non-infected outcomes — and therefore the only way to produce a rate worth comparing.
Two rechecks are recommended within the active window: at suture removal (Day 10–14) and at Week 4. Direct wound inspection by the operating surgeon is the preferred method.
Surgery
The procedure of interest. Day 0 — the anchor for every appearance interval.
First recheck
Recheck at the time of suture removal. Direct wound inspection by the operating surgeon is preferred; a trained professional or structured telemedicine review are acceptable alternatives.
Second recheck
A second recheck near the end of the 30-day window catches deep and later-appearing infections that a single early visit would miss.
Active endpoint
End of the standard active surveillance period. Any SSI linked to the procedure after this point is still recorded, with its appearance interval.
Any SSI linked to the procedure after Day 30 is still recorded, with its appearance interval — the surveillance window is the active-monitoring period, not the definition of SSI.
Without a shared definition, every term below quietly drifts between surgeons and between hospitals — and the consequences compound:
SSI rates become incomparable — between surgeons, between years, between practices.
Benchmarking and certification lose their foundation.
Research quality deteriorates; studies cannot be pooled or meta-analyzed.
Antimicrobial stewardship suffers — over-calling drives unnecessary use.
Protocol evaluation becomes weak — you cannot tell whether a change helped.
Adopting uniform definitions may initially make your SSI rate appear to rise — more intensive, consistent surveillance simply detects more. This is expected. The act of participating in surveillance is itself associated with improved prevention compliance and, over time, genuinely lower SSI rates.
Surgical site infection definitions consensus: a first step toward improving prevention in veterinary medicine.
Verwilghen DR, Pelosi A, Abbas M, et al. — American Journal of Veterinary Research, 2026
DOI: 10.2460/ajvr.25.03.0099 · Open Access — CC BY-NC
Every definition, criterion, surveillance term, and wound class on these pages derives from this expert consensus. Consensus text on each page paraphrases the paper; clinical interpretation, gray zones, and misclassification scenarios are VETSSI editorial.