Clinicopathological changes during canine transmissible venereal tumor treatment with vincristine

The aim of this study was to describe the hematological, serum chemistry and cytological changes that occur before and during regression of canine transmissible venereal tumors following treatment with vincristine. Forty-four dogs with a cytological diagnosis of TVT were treated with intravenous vincristine sulphate at a dose-rate of 0.025mg/kg body weight, for 5 weeks. At diagnosis and during follow-up evaluations, fine needle aspirate (FNA) smears, and serum samples were collected. Additionally, 11 free catch urine samples were collected at the time of diagnosis and analyzed. Of the 44 dogs examined, many were hyperglob- ulinemic (25/44, 56.8%) and anemic (19/44, 40%). Thrombocytosis was present in 25% (11/44), lymphopenia and thrombocytopenia were recorded in 13.6% (6/44), while elevated activity of lactate dehydrogenase (LDH) was recorded in 18% (8/44) of the dogs. Abnormalities in the urine samples included proteinuria and hematuria (8/11, 72%), and suppurative inflammation in 91% (10/11). Other than persistent leukopenia and thrombocytopenia in one of the dogs, all hematologic alterations had returned to within reference intervals 7 days after the first treatment of TVT with vincristine. However, reductions in serum proteins, globulins and LDH were observed after several weeks of treatment. On a weekly basis, the treatment with vincristine reduced the population of typical TVT cells, while it increased the numbers of inflammatory and epithelial cells as observed in the FNAC smears. In the present study, hematological, serum chemistry and cytological changes that occurred within the first week of treatment of canine TVT with vincristine seem to be an early indicator of eventual tumor regression. Urine is not a useful diagnostic sample for the diagnosis TVT even among dogs with bleeding genital tumors.