Canine Transmissible Venereal Tumour: An Update

Transmissible Venereal Tumour (TVT) is a naturally occurring benign reticulo-endothelial neoplastic disease usually involving the external genitalia of male and female dogs (Cohen, 1985) and also known as infectious sarcoma, venereal granuloma, transmissible lymphosarcoma or Sticker tumour.

- Tawheed Ahmad Shafi , Riyaz Ahmed Bhat, Abdul Qayoom Mir and Neha Sharma

It is common in young, sexually mature dogs (Rogers, 1997) which have an uncontrolled sexual behaviour and appears to be transmitted as cell transplant from affected to unaffected dogs usually during coitus. Laboratory transplantation of TVT from one dog to other using viable cells is also possible. In contrast to the normal number of chromosomes (78) of the species TVT cells contain an abnormal number ranging from 57 to 64 (average 59). Metastasis of TVT is uncommon, only occurring in puppies and immuno-compromised dogs. The uniqueness of TVT lies in the fact that this is the only naturally occurring tumour that is transmitted as an allograftby cell transplantation, and the tumour becomes autonomous from the original host and thus behaves like a parasite. The extensive abrasions and bleeding of the penile mucosa and vagina during coitus in dogs makes transplantations of the tumour easy.

Incidence

TVT is a serious problem around the world with temperate climates showing higher prevalence and has been also reported in India to be the most frequently reported tumour in dogs ranging from 23-43 percent of the total number of tumours in canine population. Uncontrolled sexual behaviour and a large stray dog population is one of the reasons for such a high incidence of TVT. Dogs are particularly at highest risk when females exhibit the signs of oestrus which results in enhanced sexual activity. Dogs of any breed, age or sex are susceptible.

Etiopathology and Clinical Signs