CLINICAL AND LABORATORY EVALUATION OF RESPONSE TO CHEMOTHERAPY IN CANINE TRANSMISSIBLE VENEREAL TUMOUR
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Date
2023-03-02
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR, KERALA VETERINARY AND ANIMAL SCIENCES UNIVERSITY
Abstract
A retrospective study was conducted for a three-year period at the University Veterinary Hospitals and the overall occurrence of CTVT were recorded as 0.15 percent among total cases, 0.88 per cent among total reproductive cases,
21.42 per cent among total tumour cases and 4.74 per cent among dogs with vaginal bleeding. Highest occurrence was found in Labrador Retrievers (41.30%), intact female dogs (92.22%), dogs aged 2-5 years (73.91%), pluriparous dogs (40.85%) and during south-west monsoon season (33.70%). Thirty-one CTVT confirmed dogs were randomly allocated to three treatment groups. The group I (n=13) dogs were treated with vincristine sulphate @ 0.025 mg/Kg bodyweight intravenously at weekly intervals till tumour regression. The group II (n=9) dogs were treated with ivermectin @ 200μg/Kg subcutaneously, followed by vincristine sulphate @ 0.025 mg/Kg bodyweight intravenously after 24 h and repeated at weekly intervals till tumour regression. The group III (n=9) dogs were treated with vincristine @ 0.0125mg/Kg body weight intravenously, followed by cyclophosphamide @ 5mg/Kg orally for 10 days. Vital parameters during different days of treatment were within normal limits. The body weight of CTVT affected dogs ranged from 7.0–40.5 Kg with an average body weight of 22.79 ± 1.73 Kg. Body Condition Scores BCS) were 4–5 in all dogs on all days of observation. Majority of tumours were located in the vulva (51.61%), followed by vagina (19.35%) and vestibulo-vaginal junction (16.13%), and appeared as cauliflower like friable mass that bled easily. The size of the tumour ranged from 0.9–8.5 cm with an average size of 3.90 ± 0.35 cm. A significant decrease in Canine Karnofsky Score was observed in three groups by day 21, which increased gradually. On TNM staging, majority of dogs scored T3N0M0 (54.84%), followed by T2N0M0 (32.26%) and T1N0M0 (6.45%). Two cases of metastasis (6.45%), were also reported (T3N0M1 and T4N0M1). The haemato-biochemical parameters like TEC, Hb, VPRC, TP, BUN, creatinine, albumin, globulin and ALT were within normal range. A significant difference was observed in differential leucocyte count, thrombocyte count and mean corpuscular volume (p<0.05). Significant difference were observed in AST, ALP and bilirubin values (p<0.05). On cytomorphological classification, majority of tumours were plasmacytoid (74.19%), followed by lymphocytoid (22.58%) and mixed type (3.23%). The combined malignancy scores were found to decrease after successive treatments from marked (+++) malignancy sore to absent (0) by day 21 in groups I and II and day 28 in group III. The immunocytochemical scoring with vimentin showed strong immunoreactivity on day of presentation in all dogs, and it was scored absent in group I by day 21, in group II by day 14 and in group III by day 28. The duration of treatment in vincristine, vincristine-ivermectin combination and vincristine-cyclophosphamide combination were 23.10 ± 1.49, 22.00 ± 1.00 and 30.00 ± 2.00 days, respectively. Duration of treatment and side-effects were found to be less in vincristine-ivermectin combination therapy. No recurrence of tumour was observed in three treatment groups. Considering the response to treatment, duration of treatment and intensity of side effects, combination therapy of vincristine with ivermectin gave better response in CTVT treatment. Cytology, mitotic index, apoptotic index and immunocytochemistry signalling with vimentin could be used to predict the proliferation and regression of tumour mass and thus response to therapy