Canine Transmissible Venereal Tumor: Anatomical Locations, Chemotherapy Response, and Epidemiological Aspects at a Veterinary Teaching Hospital in Brazil (2012-2022)

Abstract

Canine transmissible venereal tumor (CTVT) is a contagious neoplasm with low metastatic potential, primarily affecting free-roaming and stray dogs. Despite its global presence, epidemiological data from some regions remain limited. This study employed a retrospective observational design and analyzed 131 CTVT cases diagnosed via cytology or histopathology at a veterinary teaching hospital in Belo Horizonte, Brazil, aiming to describe the anatomical distribution, treatment outcomes, and epidemiological patterns. Most affected dogs were mixed-breed (70.2%) and female (61.1%), with a median age of 4.5 years. Genital involvement was most common (87.0%), followed by cutaneous (10.7%), nasal (6.1%), and oral (4.6%) tumors. Concurrent tumor locations included genital-cutaneous (5.3%) and oronasal (3.1%). Females had more genital cases, while males were more likely to present cutaneous and nasal CTVT, with 5.2 times greater odds for nasal tumors (OR = 5.2; 95% CI = 1.2-25.9). Purebred dogs also had increased odds of nasal involvement (OR = 8.2; 95% CI = 1.9-40.7). Vincristine chemotherapy was effective, and the number of sessions required for a complete response was not associated with clinical presentation, breed or size. These findings highlight the varied presentations of CTVT and reinforce the need for clinical awareness of non-genital forms.

Keywords: contagious; neoplasm; round cell tumor; sticker tumor; vincristine.

Figure 1

CTVT cases and incidence of CTVT per year between 2012 and 2022 at the Veterinary Hospital of the Universidade Federal de Minas Gerais, Belo Horizonte, Brazil (2021–2022).

Figure 2

Temporal distribution of CTVT cases at the Veterinary Hospital of the Universidade Federal de Minas Gerais, Belo Horizonte, Brazil (2021–2022). Grey circles: individual CTVT cases; S: newly established fixed canine sterilization centers; P: partnerships between the Zoonosis Surveillance Unit (ZSU) and civil society/nongovernmental organizations (NGOs). Created using BioRender.com.

Figure 3

Vulvar canine transmissible venereal tumor in a 1-year-old dog. Pre-treatment vulvar CTVT (A). Post-chemotherapy resolution following 4 weekly intravenous vincristine sulfate doses (0.7 mg/m²). Complete remission was achieved with no residual macroscopic disease (B).

Figure 4

Cytology of canine transmissible venereal tumor. Intense cellularity of CTVT cells. Romanowsky, 20 × 2 magnification (A). Intense cellularity of CTVT cells with mitosis and various tadpole cells. Cells present mostly plasmacytic cytomorphology. Romanowsky, 100 × 2 magnification (B).