Predicting outcomes in equine peritonitis: Multivariable analysis of admission and post-admission data from a UK hospital population.

BACKGROUND

Peritonitis is life-threatening, and limited information exists regarding outcomes and predictors of survival.

OBJECTIVES

To report short- and long-term outcomes in horses diagnosed with peritonitis and identify factors associated with survival.

STUDY

DESIGN

Retrospective observational.

METHODS

Data were obtained for horses admitted to a UK referral hospital between 2010 and 2024 diagnosed with peritonitis (peritoneal fluid nucleated cell count >10 × 109/L). Short- and long-term morbidity and mortality were assessed. Multivariable logistic regression was used to identify factors associated with short-term survival based on data available at admission (Model 1) and at the time of second abdominocentesis (Model 2).

RESULTS

Peritonitis was diagnosed in 123 horses. Overall, short-term survival was 74% (91/123) with better outcomes in primary (90%, 66/73) versus secondary peritonitis (50%, 25/50). Surgery was performed in 31 cases, with short-term survival of 48% (15/31). In model 1, horses with higher heart rates (OR 0.90, 95% CI 0.86-0.95, p < 0.001) and sanguinous peritoneal fluid (OR 0.16, 95% CI 0.04-0.65, p = 0.01) were significantly less likely to survive to hospital discharge. Survival was better in ponies vs. horses (OR 8.30, 95% CI 1.42-48.60, p = 0.02), and if rectal examination was normal (OR 8.25, 95% CI 1.80-37.85, p = 0.007). In Model 2, increased heart rate was the best predictor of reduced survival (OR 0.89, 95% CI 0.83-0.94, p < 0.001). Survival to 30, 90, and 365 days was 98% (n = 50/51), 93% (n = 42/45), and 88% (n = 35/40), respectively. A third of horses developed complications following hospital discharge (predominantly colic and pyrexia), usually within 90 days of hospital admission. Peritonitis recurred in 6 horses.

MAIN LIMITATIONS: Retrospective study from a single hospital population.

CONCLUSIONS

The prognosis for primary peritonitis is better than secondary peritonitis. Heart rate is a good predictor of short-term survival at admission and time of repeat abdominocentesis.