Thromboelastography (TEG) is an effective technique to assess the efficiency of coagulation. Phenobarbital (PB) can induce hematological and coagulation disorders in both animals and humans, but its effects on hemostasis have been little investigated and are poorly understood in dogs.
The aim of this article was to assess coagulation using TEG in a population of dogs with idiopathic epilepsy treated with PB.
Prospective observational study. TEG was performed in blood samples from dogs with idiopathic epilepsy that were divided in three groups: Two groups of treated dogs that were on phenobarbital treatment for less or more than 6 months, and a control group of healthy dogs. Duration of treatment, dose, phenobarbital serum concentration and selected hematological and biochemical parameters were evaluated and correlated with the TEG results.
No statistically significant differences were found between groups. None of the animals appeared to be in a hypo- or hypercoagulable state, however 9/19 (47,4%) dogs were classified as hyper-fibrinolytic. A statistically significant negative relationship between MA and G values and increased fibrinolytic activity (LY30) were found. No statistically significant relationship was found between PB dose or PB blood levels and TEG parameters in either group. No bleeding complications were observed.
The rise in fibrinolysis might be due to hepatic damage from PB, as indicated by elevated liver enzymes in many dogs with abnormal fibrinolytic patterns. Although TEG showed hyperfibrinolysis in some dogs, the presence of primary or secondary hyperfibrinolysis could not be confirmed due to the lack of D-dimer measurements and liver biopsy. TEG’s sensitivity compared to other fibrinolysis biomarkers like PAP might also affect results.
TThe cause of hyperfibrinolysis in epileptic dogs treated with phenobarbital remains unclear, with potential links to hepatic effects or handling, and further research is needed to assess its clinical significance.

© 2024 The Author(s). Veterinary Clinical Pathology published by Wiley Periodicals LLC on behalf of American Society for Veterinary Clinical Pathology.