Background: Procoagulant and antifibrinolytic drugs, such as formalin, aminocaproic acid (ACA), and Yunnan Baiyao (YB), are used to treat bleeding/coagulopathy in horses. Limited research supports efficacy in horses. Hypothesis/
Objectives: Formalin, ACA, or YB would alter viscoelastic coagulation in healthy horses. Animals: Seven healthy mares from university research herd.
Methods: Prospective, randomized block design with a 2-week washout between treatments. Formalin and ACA were administered slowly IV in 1L saline. YB was administered by nasogastric tube. CBC, fibrinogen, and point-of-care (POC) viscoelastic testing were performed 1hr before (T0), 1hr after treatment (T1), and at recommended redosing interval (T2; formalin 24hrs, ACA 6hrs, YB 8hrs). The effect of time was determined by one-way repeated measures ANOVA or Friedman test with post-hoc t-test or Wilcoxon test based on normality.
Results: Formalin and ACA, but not YB, showed significant effects. Formalin resulted in significant increases in A20 (p=0.01), MCF (p=0.005), LI45 (p=0.006), and platelet count (p=0.04) over time. ACA resulted in significant increases in A10 (p=0.01), A20 (p< 0.001), MCF (p< 0.001), and platelet count (p < 0.001), as well as a significant decrease in fibrinogen (p=0.001). There was no statistically significant effect of YB for any measured parameters. The ACA treatment group demonstrated significant differences between individual time points for A20 (T0 vs T1, p=0.026; T0 vs T2, p=0.047) and MCF (T0 vs T1, p=0.016). Conclusions and Clinical Importance: These results suggest that formalin and ACA promote clot formation and stability in healthy horses. Further study in horses with clinical coagulopathy is indicated.
