Bile Acids, Direct Bilirubin and Gamma-glutamyltransferase as Prognostic Indicators for Horses with Liver Disease in the Eastern United States: 82 Cases (1997-2019).
Authors: Delvescovo Barbara, Tomlinson Joy, DeNotta Sally, Hodge Elizabeth, Bookbinder Lauren, Mohammed Hussni O, Divers Thomas J
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Elevated bile acids and gamma-glutamyltransferase are routinely measured to assess hepatic dysfunction in horses, yet their prognostic value remains unclear. A retrospective analysis of 82 cases from four eastern US referral hospitals examined whether the magnitude of these liver-specific markers, alongside direct bilirubin and histological fibrosis, could predict survival in horses with confirmed liver disease over a minimum six-month follow-up period. Whilst elevated bile acids and GGT showed no statistical association with outcome, direct bilirubin emerged as a significant prognostic indicator—each unit increase in direct bilirubin concentration nearly doubled the odds of non-survival (OR 1.95, 95% CI 1.34–3.19). Surprisingly, the presence of fibrosis on biopsy alone did not differentiate between survivors and non-survivors, challenging the assumption that histological changes are reliable prognostic markers. Clinically, these findings suggest that relying on markedly elevated bile acids or GGT values to counsel owners on prognosis may be misleading, and instead direct bilirubin should be weighted more heavily when estimating survival outcomes, though serial monitoring and individual case context remain essential components of prognostication in equine liver disease.
Read the full abstract on PubMed
Practical Takeaways
- •When evaluating horses with liver disease, prioritize direct bilirubin levels as a prognostic indicator rather than relying on bile acid or GGT values alone
- •Do not use the presence of fibrosis on liver biopsy as a sole prognostic indicator—horses with fibrosis may still survive with appropriate management
- •Consider direct bilirubin concentration as part of a multi-factor assessment when counseling owners about prognosis and treatment decisions in equine liver disease
Key Findings
- •Direct bilirubin concentration was positively associated with non-survival (OR 1.95, 95% CI 1.34-3.19, P = 0.0023), making it a significant prognostic indicator
- •The magnitude of bile acid elevation (>30 µmol/L) was not related to outcome (OR 0.9999, P = 0.97)
- •Gamma-glutamyltransferase activity degree was not associated with prognosis (OR 1.0, P = 0.31)
- •Presence or absence of fibrosis on liver biopsy was not associated with outcome (P = 0.37)