Clinical Guidelines for Canine Transmissible Venereal Tumour Treatment: Systematic Review and Meta-Analysis

The treatment of canine transmissible venereal tumour (CTVT) has evolved since its initial description in 1810. Initially considered untreatable in the early 20th century, extensive research over time has significantly advanced our understanding of its aetiopathogenesis. This led to successful chemotherapy treatments, which have shown superior outcomes compared to surgical interventions. Vincristine, in particular, has proven effective in treating CTVT. However, the development of chemoresistance underscores the need to explore alternative therapeutic options. This systematic review provides a comprehensive analysis of CTVT treatment practices from 1950 to 2023, aiming to establish a gold standard and enhance clinical decision-making. Initially, 3633 studies were identified, with 42 meeting the eligibility criteria. Our findings suggest that vincristine sulphate monotherapy is the recommended first-line treatment for CTVT. Administering vincristine intravenously at a dosage of 0.5-0.75 mg/m² weekly for 4-6 sessions resulted in a 93.1% (67.4%-100%) complete response rate in dogs. Extending the treatment to eight sessions increased the complete response rate to 98.9% (83.3%-100%). Radiation therapy, lomustine and doxorubicin are viable second-line treatment options; however, extensive cohort studies are required to confirm their efficacy in achieving remission in vincristine-resistant cases. Additionally, no clear criteria could be established for initiating treatment with drugs other than vincristine in previously untreated dogs. Surgery is considered a third-line option. Notably, complete remission is anticipated following recommended systemic and local therapies in nearly all cases. Despite concerns about chemoresistance, current guidelines indicate a favourable response to suggested treatments even in resistant cases.