This study analyzes the clinical aspects of contaminated and infected synovial cavities in horses and evaluatestheir prognosis after treatment. The medical records of 195 affected horses referred between June 1999and July 2004 were reviewed. Twenty-six horses were euthanized or returned home without further treatment.Therapeutic strategies for the remaining 169 horses were not different from those reported in other recentstudies, except that lavage was performed predominantly without endoscopic visualization. Follow-up wasobtained by questionnaire for 150 of 169 treated horses. The outcome was considered successful (survival withoutresidual lameness) in 109 of 150 horses (72.7%). Iatrogenic synovial infection, the presence of radiographicsigns on admission and the use of regional antibiotic perfusion were significantly related withnon-successful outcome. Overall, the outcome in the present study appeared to be slightly less favorable comparedto other recent reports, although it certainly improved for horses with deep nail puncture wounds.