Alterazioni emostatiche nel linfoma canino: contributo sperimentale

Abstract

Lymphoma is the most common haematopoietic malignancy in dogs, and the aim of this study was to evaluate the presence of hemostatic and coagulative changes related to this disease. In fact in Human Medicine it is well known that coagulative disorders, such as DIC and thromboembolism, are often a consequence of neoplastic diseases and of lymphoma in particular. The pathogenesis of the thromboembolic disease in haematological tumors is complex and multifactorial, but a crucial role seems to be played by the activation of the tissue factor (TF), which may derive from tumor cells or may originate from the tumor-associated environment (endothelial cells or blood cells) in response to inflammatory mediators. Although in Veterinary Medicine there are fewer studies available on the association between malignant neoplasms and haemostasis, this link has been evaluated also in the canine species. The development of hemostatic alterations is in fact one of the most common paraneoplastic syndromes of the dog: as complications of neoplasms, patients can develop disorders ranging from hemorrhagic diathesis to thrombosis. In particular, canine lymphoma has been associated with hypercoagulability and subsequent thromboembolism, which may contribute to the mortality associated with the disease. It was therefore carried out a retrospective study to assess the presence of alterations of the hemostatic parameters in a group of dogs affected by B or T lymphoma, comparing them with the same number of animals not affected by this disease (control group). Eight parameters were evaluated (plt, aPTT, PT, TT, fibrinogen, FDPs, D-dimers, AT), and the most significant alterations were found to be those affecting the fibrinogen. In fact, dogs with lymphoma had a statistically significant hypofibrinogenemia that also influenced the alteration of the other parameters. This condition of hypofibrinogenemia, more than by an excessive consuption of fibrinogen due to a state of hypercoagulability (presence of DIC or thromboembolism in animals with lymphoma), can be explained by a lower production of fibrinogen due to liver involvement by the tumor, or by the presence of a hemophagocytic syndrome, which can be related to lymphoma and has hypofibrinogenemia among its characteristics. Knowing that hemostatic alterations may occur in association with lymphoma is very useful to better define patient management, therapy and prognosis. However, further studies are necessary to better define and understand the phenomenon and the underlying pathogenetic mechanism.