Atypical Presentation and Aggressive Behavior of the Transmissible Venereal Tumor in a Dog: A Case Report

Introduction: The present report aimed at describing an atypical presentation of a cutaneous transmissible venereal tumor (TVT) in a dog. Case Presentation: The case was admitted at the Veterinary Hospital of the Universidade Estadual Paulista (UNESP), Jaboticabal, São Paulo, Brazil, due to the presence of multiple ulcerated, crusty, and occasionally coalescing cutaneous nodules. The disease was first diagnosed by a practitioner 15 months before the referral to the UNESP Veterinary Hospital. Thus, the dog had already been subjected to the vincristine antineoplastic chemotherapy for the treatment of cutaneous TVT 15 months ago. As a diagnostic approach, cytological, histopathological, and immunohistochemical analyses were performed. The patient was then subjected to antineoplastic chemotherapy based on vincristine, doxorubicin, and bleomycin protocols; nonetheless, it was not successful, and the patient passed away 16 months after the primary diagnosis of TVT. Conclusions: TVT can be more aggressive than usually expected, and the correct diagnosis and appropriate treatment can reduce the risk of chemotherapy resistance.