Canine transmissible venereal tumor（CTVT）is a common directly transmissible round cell tumor in dogs. This report describes a case of CTVT in a 6?year?old intact male Golden Retriever. The dog was presented with dysuria，urine dribbling，and frequent licking of the genital area. Based on the mating history and local examination，a nodular proliferation with an irregular surface that bled easily on contact was identified at the distal glans penis. Urinary catheterization could be performed slowly，indicating that the local mass had caused urethral irritation or compression，but not complete obstruction. Complete blood count and serum biochemical revealed no obvious abnormalities. Histopathological examination showed diffuse proliferation of round tumor cells with prominent cytoplasmic vacuolation， distinct nucleoli， and frequent mitotic figures， confirming the diagnosis of CTVT. Considering the distal genital location of the lesion，the marked local irritation，and the associated urinary dysfunction，tumor excision combined with castration was performed，followed by postoperative intravenous vincristine chemotherapy（0.54–0.76 mg per treatment，once weekly for 4 weeks）. After treatment，the dog showed only mild lethargy. The surgical site healed well，urination returned to normal，and no local recurrence was observed during follow?up. This case suggests that，for genital CTVT with local functional involvement，individualized treatment should be planned based on a comprehensive assessment of lesion extent and local effects. For localized cases with marked local symptoms and a need for rapid reduction of tumor burden，surgery combined with postoperative vincristine chemotherapy may have practical clinical value.