TVT is the most prevalent tumor of the genitalia of the either sex of dog, but cutaneous form of TVT is uncommon. The etiology of TVT is not completely known, but it can transmit from affected dogs by coitus and/or by natural contact
(Gurel et al., 2002). In the present case the cutaneous mass appears to be due to metastasis and spreading of tumor cells (Fig 1A). TVTs are immunogenic tumors and the immune system of the host plays a major role in inhibiting tumor growth and metastasis (
Cohen, 1985). In present study, we observed that the tumour masses on the vagina and vulva which was irregular in shape with cauliflower like appearance and reddish in colour. The consistency of the mass was soft and had a tendency to bleed (Fig 1). The dramatic reduction in gross tumor size was observed by 7 day after the first dose of Vincristine and full-response by 28 day (Fig 1B).
Martins et al., (2008) also did similar treatment and found gradual tumor response although the response was noticeable and significant at the beginning of treatment which regressed gradually later.
Valladao et al., (2010) administered similar treatment with Inj. Vincristine @ 0.025 mg/kg i/v at weekly intervals for five weeks with which complete remission was achieved in 75 dogs with a median of 5 Injections. Said
et. al., (2009) also treated similarly and found that the treatment was 90% effective.
Khan et al., (2009) enumerated that Inj. Vincristine gave promising result in respect to granulomatous growth from penis in male, vaginal canal in females which disappeared in 21 days. On cytology, TVT cells showed a predominance of round cells with abundant pale cytoplasm and distinct, punctate cytoplasmic vacuoles. The cytoplasm of the tumour cells was greyish in colour when stained with Giemsa stains (Fig 2). Typical cytological analysis showed slightly polyhedral cells. The nature of cellularity was high with homogenous round individual cells arranged in a sheet-like pattern. A great variation in the cellular (anisocytosis) and nuclear morphology (anisokaryosis) was observed. The nucleus of the tumour cells was round to oval in shape and centrally placed. The most prominent cytological feature of TVT is the presence of distinct, clear, cytoplasmic vacuoles often referred to as punctate vacuoles with a delineated outline. The nuclear to cytoplasmic ratio of tumour cells was large (Fig 2).
@figure3
Similar cytological features were reported by many researchers (Alleman and Bain, 2000; Duncan and Prasse, 1979;
Fan et al., 2001; Meinkoth and Cowell, 2002). Ulcar
Igor et al., (2012) reported cytological evaluation of tumors of genital tract in dogs are essential for diagnosis and the cytological features of the genital tumors have typical criteria of TVT. TVT dogs of the present study showed significant (P<0.05) value of Hb, WBC, Eosinophil, BUN and SGOT from day 0 to day 28 during before and after treatment. We observed 14.10±0.28 and 13.50±0.29 gm/dl of Hb before and after treatment respectively. Similarly, WBC count before and after treatment were 10266.66±176.38 and 11533.33±185.59 respectively. The eosinophil value recorded were 6.33±0.33 and 2.67±0.33 respectively before and after treatment. BUN value we found were 7.17±0.20 and 11.63±0.21 whereas, SGOT were 43.00±1.73 and 31.67±1.45 before and after treatment respectively (Table 1).
The hematological findings were in contrast to
Das et al., (1991). Tella et al., (2004), Said et al., (2009) and
Nak et al., (2005) opned that decrease of Hb, PCV and TEC may be attributed to the tumoural bleeding and myelosuppression induced by chemotherapeutic drug. Leucocytosis which was observed in the present study was similarly observed by
Girmabirhan et al., (2015) and
Behera et al., (2012). Results indicates that all the TVT affected dogs showed significant increase of BUN and no change in serum creatinine, incompatibility.
Albanese et al., (2006), Gandhimathi et al., (2011) and
Girmabirhan et al., (2015) reported that normal physiological range to mild increase of BUN and serum creatinine was seen in TVT affected dogs. Some researcher also shows that SGPT and SGOT showed significant increase (P<0.01) after treatment when compared to day 0 which are at par of our result
(Behera et al., 2012: Girmabirhan et al., 2015; Albanese et al., 2006 and
Gandhimathi et al., 2011). Hematology was indicative of marked microcytosis and thrombocytopenia owing to immunosuppressive nature of the disease, leading to secondary bacterial invasion.
Treatment of dog with TVT
Chemotherapy was initiated with Vincristine sulfate @ 0.025mg/kg bwt IV once a week for 4 weeks. Animal showed clinical improvement from 2
nd week of chemotherapy and complete uneventful recovery was noticed after 5
th weeks of Vincristine sulfate chemotherapy. Vincristine sulfate acts by binding to tubulin dimer which is necessary for mitosis of spindle fibers, contributing to cellular division arrested in metaphase stage (
Coppoc, 2009).
