Progressive Type of Canine Transmissible Venereal Tumor ( CTVT ) in a Male Stray Dog : a Case Report

Department of Pathology and Parasitology, Faculty of Veterinary Medicine, Chittagong Veterinary and Animal Sciences University, Khulshi, Chittagong–4202, Bangladesh; Department of Anatomy and Histology, Faculty of Veterinary Medicine, Chittagong Veterinary and Animal Sciences University, Khulshi, Chittagong–4202, Bangladesh; Department of Microbiology and Parasitology, Faculty of Animal science and Veterinary Medicine, Sher–e–Bangla Agricultural University, Sher–e–Bangla Nagar, Dhaka–1207. Bangladesh; Chittagong Veterinary and Animal Sciences University, Khulshi, Chittagong–4202, Bangladesh *Corresponding author: si.mamun@ymail.com

The canine transmissible venereal tumor (CTVT) is a benign reticuloendothelial neoplasm producing cauliflower like, firm to friable nodular mass on the external genitalia of either male or female dogs and it occur at the same frequencies in both sexes (Rogers, 1997).It is known to be the most frequent tumor in ownerless stray dog population that usually copulate freely (MacEwen, 2001).The tumor may be single or multiple, nodular or pedunculated, ranging from a small nodule less than a centimeter to over ten centimeter (Deborah, 1995).CTVT can be diagnosed histopathologically by round, ovular polyhedral cells with indistinct poor cytoplasmic boundaries.Characteristic multiple cytoplasmic vacuoles and large foamy nuclei are the common cytological features of such tumor cells (Tasqueti et al., 1999).
An adult indigenous (non descriptive breed) male stray dog of 30 kg body weight was brought to SAQ Teaching Veterinary Hospital, Chittagong Veterinary and Animal Sciences University (CVASU) having prolonged history of cauliflower like growth and blood stained discharges from the penile region (Figure 1A, 1B).During physical examination, the penile sheath of the dog was found obscure and swollen.Besides, physically the blood stained flesh was visible with bad odor from a distance.The local municipal authority and duty doctors of the hospital decided to perform euthanasia.Detailed clinical and histopathological examination of the tumor mass was performed.Cardinal parameters revealed rectal temperature 38.5 0 C, respiratory rate 20 breaths/min and heart & pulse rate 102 beats/min, all these parameters were within the normal range.The observed tumor mass was examined for cytology using fine needle aspiration biopsy following the procedures described in Cowell et al. (2008).It was decided after complete clinical and histopathological findings that euthanasia may be performed.Following complete sedation of animal, the 30ml of saturated MgSO 4 was injected intracardially for performing euthanasia.The dog was necropsied at the pathology laboratory of Department of Pathology and Parasitology, CVASU at the earliest possible time of euthanasia.Necropsy was performed as per standard method described in Coles (1986).At necropsy, gross tissue changes were observed carefully and recorded.For histopathological study tissue samples were fixed in 10% buffered formalin and dehydrated in graded 100% ethanol and embedded in paraffin wax.Fixed tissues were sectioned at 5 μm thickness and stained with hematoxylin and eosin as per standard method (Luna, 1968) for microscopic examination.

Progressive Type of Canine Transmissible Venereal Tumor (CTVT) in a Male Stray Dog: a Case Report
In this study aspiration biopsy of the tumor mass exhibited numerous round cells with moderate amount of pale finely granular cytoplasm with multiple sharply defined vacuoles where nuclei of the cells seem slightly eccentric and coarse with mitotic figures (Figure 2A, 2B) these findings are with complete agreement as described by Tasqueti et al. ( 1999).At necropsy, multiple rounds to oval, firm nodular mass, ranging from 5 cm to 9 cm diameter (Figure 3) were observed throughout the subcutis, mainly at the preputial mucosa and cranial to the glans penis.There was no gross changes observed anywhere other than penile region in the infected dog.From the excised tumor mass, histopathological examination revealed sheets of large round cells resembling lymphoblast (Figure 4).However, the nuclei of the cells are larger than those of lymphoid cells.
The round or slightly indented nuclei stained more hyperchromatically than those of lymphoblasts and showed pronounced variation in size.Regression is associated with increased numbers of tumorinfiltrating lymphocytes and is characterized by increased apoptotic tumor cells and fibrosis.As suggested by the histopathological features in the present case, there is minimal involvement of tumor infiltrating lymphocytes and high numbers of mitotic figures which designate it as progressive phase of CTVT (Figure 5).Histological features of regional lymphnodes, spleen or viscera of the infected dogs did not show any evidence of metastasis.
In the present case, as the dog was a stray and duty doctors of the hospital with the consent of local municipal authority has decided to perform euthanasia instead of any treatment approaches, no such attempt was taken.But surgery has been extensively used for the treatment of TVT even though recurrence rate is said to be high (Rogers, 1997).The histopathological features of the tumor lesions in present the case confirmed a progressive phase CTVT in penile region without any evidence of metastasis.However, detailed analysis of the origin of these round (tumor) cells types was not determined.Finally, this is possibly the first case report in regarding progressive type CTVT in a male stray dog at Chittagong, Bangladesh.

Figure 1 :
Figure 1: Large cauliflower-like growth, along with bloody discharge from penile region

Figure 3 :
Figure 2: A. Numerous round cells with coarse eccentric nuclei and pale finely granular cytoplasm with mitotic figures in Giemsa stained smear (40X); B: Multiple sharply defined vacuoles seen within the round cells cytoplasm (100X)