In this study, 12 dogs affected by canine
transmissible venereal tumor (CTVT) and testicular
seminoma tumor were studied retrospectively. The cytological sample was smeared onto a glass slide and either air-dried for May-Grünwald-
stain, and masses were surgically removed. The
tumors were grossly examined, and sections of 4-μm thick were obtained from each sample and stained with H&E. For
chemotherapy,
vincristine sulfate was administered weekly as an infusion over 3 min via the cephalic vein at a dose of 0.025 mg/kg after diluting with physiological saline to a total amount of 10 ml. If no remission was observed after 8 weeks,
chemotherapy was continued with weekly
doxorubicin infusion at a dose of 1 mg/kg. All the
tumor samples were divided into four cytohistopathologic groups, namely: multilobular (six cases), papillary (two cases), pedunculated (two cases), and tubular (two cases of
seminoma). The most frequently represented
tumor type was multilobular (6/10, 60 %) followed by pedunculated (2/10, 20 %), papillary (2/10, 20 %), and tubular (two cases of
seminoma, 100 %). Cytological smears from eight
tumors in regression after
chemotherapy were poorly cellular, and many cells were fragmented. In two progressive
tumors, there was an average of 1,406 ± 972 CTVT 200 cells/μl or 96.71 % of total cells counted. Thus,
tumor cells represented 96.71 % of total cells within the biopsy specimens and the leukocytes 4.29 % (leukocyte,
tumor cell ratio=0.062 ± 0.031). In eight regressive
tumors, there was an average of 1,245 ± 1,032 CTVT 200 cells/μl or 97.31 % of total cells counted. Thus,
tumor cells represented 97.31 % of total cells and leukocytes 2.69 % (leukocyte,
tumor cell ratio=0.071 ± 0.174). Our data suggested that combination treatment with
vincristine and
doxorubicin in the future could be an excellent therapeutic alternative for the treatment of TVT for probably reducing the resistance to
vincristine, and also, treatment success could easily be followed by the cytological changes.