RAMA DEVI, V (MAJOR)SATHEESH, KRAVI KUMAR, PSUDHAKAR, KSUDHA RANI CHOWDARY, CH.2021-09-042021-09-042020-10https://krishikosh.egranth.ac.in/handle/1/5810175063THESESThe present study was undertaken to know the occurrence of canine mammary tumors (CMTs), to classify and study their gross and microscopic lesions, evaluate different tumor markers by IHC and to determine the variations of p53 gene in CMTs. In the present study, the animals with mammary tumors ranged from 1.5 to 14 years of age with highest occurrence in 9-10 years age group and noticed only in female dogs. Highest occurrence of canine mammary tumors was recorded in non-descript dogs followed by Spitz and German Shepherd breeds. The occurrence was highest in intact bitches when compared to spayed dogs. Out of 72 cases, 47 cases had a single mammary gland affected whereas 25 cases had tumors in multiple glands. The highest occurrence was recorded in the inguinal (50.49%), followed by caudal abdominal (33.98 %) glands. Majority of the cases showed TNM stage III tumors (59.42%), followed by stage II (21.74%), stage IV (8.7%), stage V (7.25%) and stage I tumors (2.90%). Overall, the cytological diagnosis had 75% correlation to histopathological diagnosis. The cytologic diagnosis correlated with the histologic diagnosis for benign and malignant tumors in 60 and 79.59% of cases respectively. Grossly, the size of the tumors ranged from 2 to 19 cm in greatest diameter with different shapes and consistencies. Sixty three cases (87.5%) had malignant tumors and 9 cases (12.5%) showed benign tumors. Histologically, they were classified into 20 major subtypes and among them, solid carcinoma had the highest frequency (20.6%), followed by complex carcinoma (15.9%), intraductal papillary carcinoma (14.3%). In the present study, metastasis of CMTs to lymphatic vessels, lymph nodes and visceral organs was recorded in 13 cases (18.1%). Maximum number of carcinomas were of grade II (46.7%) followed by grade III (40%) and grade I category (13.3%). The mean AgNOR number per cell ranged from 1.1 to 6.7 and was higher (4.58) in malignant tumors than in benign tumors (1.4). Of the 72 CMTs subjected to immunostaining of different tumor markers, 38.9% of tumors showed Ki-67 expression, 37.5% and 25% of CMTs showed ERα and PR expression respectively, whereas 89.1%, 25% and 16.7 % of the cases showed VEGF, survivin and p53 expression respectively. Of the 20 CMTs subjected to molecular studies, three mutations in exon 4 were detected in two tumor tissues which included two missense mutations in a complex carcinoma and a silent mutation in a carcinosarcoma. However, concordance of p53 phenotype and p53 genotype was found only in one case which had a silent mutation. On Kaplan - Meier analysis, early TNM stage, positive expression of ERα and PR, negative expression of p53 and survivin were found to be associated with longer overall survival. However, only TNM stage and PR expression were found to be independent prognostic factors on multivariate analysis. In the present study, various factors such as tumor stage, histological grade and features, expression of different tumor markers and p53 gene variations along with epidemiological data were evaluated in CMTs. It was revealed that the factors like TNM stage and PR expression have significant prognostic value and can influence the clinical outcome of canine mammary tumors.EnglishThesis