Temporospatial distribution and country of origin of canine transmissible venereal tumours in the UK

Transmission of canine transmissible venereal tumour between two dogs in the UK

Canine transmissible venereal tumour (CTVT) is a contagious cancer spread by transfer of living cancer cells. Occasional cases are observed in the UK in dogs imported from endemic regions. Here, we report a case of imported canine transmissible venereal tumour that was transmitted to a second dog within the UK. Transmission of genital canine transmissible venereal tumour occurred despite neutered status of the second dog. The aggressive course of disease in both cases, which included metastasis, resistance to therapeutic interventions and ultimate euthanasia of both dogs, is described. The diagnosis of canine transmissible venereal tumour was made using a combination of cytology, histology, immunohistochemistry and PCR to detect the LINE-MYC rearrangement. Practitioners unfamiliar with canine transmissible venereal tumour are reminded of this disease of concern, particularly when imported dogs are placed in multi-dog households, irrespective of neuter status.

Sex disparity in oronasal presentations of canine transmissible venereal tumour

BACKGROUND

The canine transmissible venereal tumour (CTVT) is a contagious cancer spread by the direct transfer of living cancer cells. CTVT usually spreads during mating, manifesting as genital tumours. However, oronasal CTVT is also occasionally observed, and presumably arises through oronasal contact with genital CTVT tumours during sniffing and licking.

METHODS

Given that sniffing and licking transmission behaviours may differ between sexes, we investigated whether oronasal CTVT shows sex disparity.

RESULTS

Twenty-seven of 32 (84%) primary oronasal tumours in a CTVT tumour database occurred in males. In addition, 53 of 65 (82%) primary oronasal CTVT tumours reported in the published literature involved male hosts. These findings suggest that male dogs are at four to five times greater risk of developing primary oronasal CTVT than females. This disparity may be due to sex differences in licking and sniffing activity, perhaps also influenced by sex differences in CTVT accessibility for these behaviours.

CONCLUSION

Although oronasal CTVT is rare, it should be considered as a possible diagnosis for oronasal tumours, particularly in male dogs.

Canine Transmissible Venereal Tumor: An Infectious Neoplasia in Dogs

Canine transmissible venereal tumor is the oldest cancer in dogs and is transplanted via viable cancer cells. This cancer has a specific host, easy transmission, noticeable gross lesions, a predictable growth pattern, an immunologic relative host response, unique molecular characteristics, and is responsive to chemotherapeutic treatment. These points make researchers and practitioners interested in this cancer. Genital cases are noticeable and therefore easier to diagnose and treat than extragenital cases. By contrasting the anatomical features of the two types of cases, we highlight the uniqueness of canine transmissible venereal tumors and discuss the diagnosis, treatment, and prevention of this ancient cancer.