Prevalence of different cytomorphological types of transmissible venereal tumours and the association with prognosis in dogs treated with vincristine sulphate – Retrospective study

Abstract

Canine transmissible venereal tumours (CTVT) are the most commonly diagnosed tumours in veterinary hospitals. CTVT is morphologically classified as a round cell tumour, although the exact origin of the cells is unknown. Immunohistochemical studies have suggested histiocytic and mesenchymal origin. CTVT can be classified as lymphocyte-like, plasmocyte-like, and mixed according to their cytomorphological features. The treatment of choice for CTVT is chemotherapy with vincristine sulphate applied weekly; this produces a good prognosis. However, an increase in the number of chemotherapy applications and adjuvant therapies has become common. The aim of this study was to determine the association of cytomorphological types of CTVT with resistance and partial resistance to vincristine sulphate and the possible need for a large number of chemotherapy sessions. A retrospective study of a 24-month period evaluated 46 diagnosed and treated cases of CTVT. It was concluded that there is a higher prevalence of plasmacyte-like, followed by mixed and lymphocyte-like CTVT. The cytomorphological type did not differ in relation to the response to the treatments with vincristine sulphate and the number of chemotherapy sessions necessary for CTVT regression has increased by factors not yet elucidated.