Annual Research & Review in Biology

Canine transmissible venereal tumour (CTVT) is a naturally occurring contagious round-cell neoplasm of dogs that most commonly affects the external genitalia. A 12-year-old non-descript intact male dog weighing 25.4 kg was presented with a one-month history of persistent preputial bleeding and proliferative penile masses. The dog had mated approximately two months before presentation. Clinical examination revealed multiple firm, ulcerated, cauliflower-like masses over the penis, accompanied by serosanguineous discharge. Diagnostic evaluation comprised a complete blood count, serum biochemical assessment, thoracic and abdominal radiography, and fine-needle aspiration cytology. Survey radiographs showed no evidence of internal metastasis. Giemsa-stained cytological smears contained numerous round cells with round-to-oval nuclei, mildly basophilic finely granular cytoplasm, and distinct peripheral cytoplasmic vacuoles, confirming transmissible venereal tumour. The dog received vincristine sulphate intravenously at 0.025 mg/kg once weekly for five consecutive weeks. Following treatment, the masses regressed completely, preputial bleeding and penile discharge resolved, and no noticeable adverse haematological or biochemical changes were detected. No clinical recurrence was observed during the subsequent two-month follow-up period. This case demonstrates a favourable clinical response to weekly vincristine sulphate in an aged male dog with cytologically confirmed genital CTVT. The findings should be interpreted within the limits of a single case and the relatively short follow-up period.