Thrombosis is a common complication following splenectomy in both human and veterinary medicine. In human studies, post-splenectomy portal vein thrombosis rates range from 4.7-6.6%, while a veterinary study reported a 7.6% perioperative mortality rate, with thrombosis suspected as the cause in 32% of cases. Risk factors for thrombosis include Virchow’s triad and thrombocytosis, with patients typically experiencing a hypercoagulable state due to elevated platelet counts 2-3 days post-surgery. In dogs undergoing splenectomy for splenic masses, similar thrombotic risks, such as portal vein thrombosis and pulmonary thromboembolism, are observed.
Platelets are activated in response to various mediators, including adenosine diphosphate (ADP) and thrombin, leading to aggregation and clot formation. Clopidogrel, an antiplatelet agent, inhibits platelet activation by blocking the P2Y12 ADP receptor. This study hypothesized that clopidogrel would reduce thrombocytosis and hypercoagulability in dogs post-splenectomy, aiming to evaluate its effects on platelet counts and coagulation over the first two weeks after surgery.
Twelve dogs undergoing splenectomy were divided into two groups: group A received no treatment, and group B received clopidogrel. Blood samples were collected at anesthesia induction, and on days 2, 7, and 14 post-splenectomy, to measure packed cell volume (PCV), platelet count, and thromboelastography (TEG) parameters. Group B received a loading dose of 10 mg/kg clopidogrel on day 2, followed by 2 mg/kg daily until day 14. Adverse drug reactions were monitored at each time point.
The study found no significant differences in PCV, platelet counts, or TEG parameters between the two groups at any time point. Platelet counts increased on day 2 after splenectomy, with thrombocytosis commonly observed in both groups during the first two weeks, which aligns with prior research. However, by day 14, group B exhibited a significant decrease in platelet counts compared to group A, suggesting a potential effect of clopidogrel. Despite this, the mechanism behind clopidogrel’s effect on platelet counts remains unclear, and uncontrolled variables such as inflammation and fibrinogen concentration may have influenced the results.
No adverse effects, including bleeding or gastrointestinal issues, were observed in group B, suggesting that clopidogrel is safe for use starting from day 2 after splenectomy. However, the study’s small sample size and lack of breed diversity limit the generalizability of these findings, and further research with larger cohorts is needed to confirm clopidogrel’s safety and efficacy.
In human medicine, the risk of thrombotic complications following splenectomy has decreased with better understanding of associated risks. While veterinary studies on splenectomy complications are ongoing, they are still limited. Splenectomy is most commonly performed in humans for trauma, immune thrombocytopenic purpura, or cancer, while in dogs, 48-59% of splenic tumors are malignant.
The study found thrombocytosis to be common in dogs after splenectomy, with clopidogrel administration leading to a reduction in platelet count by day 14. This decrease was correlated with changes in TEG parameters, indicating that platelet regulation may help mitigate hypercoagulability. However, due to study limitations, such as sample size and the potential influence of uncontrolled variables, further studies are required to validate these findings.
