Keshaw Prasad Tiwari¹, Muhammad Iqbal Bhaiyat¹, Alfred Chikweto¹, Allison Inga¹, Ravindra Nath Sharma^1*, RVS Pawaiya^2
1Pathobiology Academic Program, School of Veterinary Medicine, St. George’s University, Grenada, West Indies; ²Central Institute for Research on Goats, Makhdoom, P.O. Farah–281122, Mathura, Uttar Pradesh, India
*Corresponding author: rsharma@sgu.edu

ABSTRACT
A study was undertaken on 40 round cell tumors in dogs namely, transmissible venereal tumor (TVT), 19 cases; mast cell tumor (MCT), 7 cases; canine cutaneous histiocytoma (CCH), 14 cases. These tumor cases were selected from biopsy and necropsy submissions for the period 2001 to 2011 on dogs residing in Grenada. The objective of this study was to evaluate the expression pattern of the tumor suppressor protein p53 in these tumors. Nuclear expression of p53 was detected as moderate to strong immuno–reactivity in most of the 3 tumors under study. The percentage of immuno–marked cells was 36.8, 50.0, and 57.1 for TVT, CCH and MCT, respectively. Intensity of p53 immunostaining was proportional to biological behavior of the tumors. Canine TVT in metastatic sites showed significantly (P=0.009) higher immune–reactivity compared to TVT in primary site. Strongly positive p53 expression was seen consistently in TVT at extragenital sites indicating a higher degree of malignant behavior of this tumor. This suggests that p53 expression could be a useful indicator of the malignant potential and prognosis of canine TVT.

Key Words: Cutaneous histiocytoma, Mast cell tumor, p53, Transmissible venereal tumor, tumor suppressor protein, Dog, Grenada