Canine transmissible venereal tumor: A review

Abstract

Canine Transmissible Venereal tumor (TVT) is one of the most commonly occurring benign reticulo-endothelial tumor of dogs affecting both the sexes. It is mostly transmitted by coitus with incidence rates ranging from 2 to 43% of all tumors prevalent in temperate climate and both young and sexually mature age groups are affected. Such tumor presents abnormal numbers of chromosomes ranging from 57 to 64 and averaging 59 (58 ± 5), in contrast to the normal 78 chromosome found in the species and is the only proven example of tumor that is transplanted as an allograft during cell transplantation. Metastases cases are uncommon but puppies and immune-compromised dogs are at greater risk. The etiology appears to be tumoral cell transplantation from affected host to healthy animals. Prevalence of this tumour was reported to be 23.5% to 28.6% in Punjab 28.6% in Andhra Pradesh and 42.8% in the state of Assam. Clinical cases are usually presented with tumor localized in the shaft of penis in males and along the vestibule of vagina in females. Small nodular lesions that bleed easily are the most consistent clinical finding. Cytological studies of smears made from such tumor reveals round cells with clear cytoplasmic vacuoles, mitotic figures with chromatin clumping and presence of one or two prominent nucleoli. The tumor is self-limiting and vincristine sulfate is currently the most effective therapy. Immune modulation therapy is yet to be validated for treatment purposes. The present review throws a light and narrates some of the critical aspects such as incidence, prevalence, transmission pattern, gross and microscopic findings and the treatment regime of dogs affected with TVT.