The research on feline reproductive pathology is very nascent in India. Disorders affecting the ovaries and uterus can significantly impact the overall reproductive health and wellbeing of the animals. Cats, known for their independent nature and graceful demeanor, are often cherished as beloved companions, making their reproductive health a primary concern for owners and veterinarians alike. Understanding the complexities of reproductive tract abnormalities in these feline companions is crucial for timely diagnosis, effective management, and the preservation of their health and reproductive capabilities. Enhanced knowledge on basic reproductive pathology of the queen cat is essential for taking advantage of the techniques for assisted reproduction, diagnosis of uterine and ovarian pathologies in several species including wildlife. Hence, the present study was undertaken in order to establish the incidence of reproductive disorders and to determine gross, associated cytological, histopathological, immunohistochemical changes in various pathological conditions of feline ovary and uterus.

A total of 70 ovaries were collected from 35 queen cats irrespective of age and breed. Among them 51 ovaries (73%) showed different ovarian lesions such as nonneoplastic and neoplastic which accounted for 49% (34 cases) and 24% (17) cases respectively and the remaining 27% (19) ovaries were normal. The most common lesion noticed was follicular cyst in about 26 cases (37.14%) then followed by interstitial endocrine cell hyperplasia, the second most common lesion reported in thirteen ovarian sections (18.5%). The other lesions noted were luteal cyst in eight cases (11.4%), oophoritis in eight cases (11.4%), embedded corpusluteum in three cases (4.28%), follicular atresia in three cases (4.28%),cavernous hemangioma in three cases (4.28%), hemangiopericytoma in three cases (4.28%), histiocytoma in three cases (4.28%), hemangiosarcoma in two cases (2.85%), granulosa cell tumor in two cases (2.85%), polyoogonia in two cases (2.85%), folliculoid in two cases (2.85%), serous inclusion cyst in two cases (2.85) and smooth ovary inonecase (1.42%). Vascular disturbances were noticed in twenty cases (28.5) along with other ovarian lesions.

Gross observations revealed mild enlargement and irregular ovarian surfaces associated with different types of cysts. The most prevalent lesion, follicular cysts grossly exhibited as clear straw coloured fluid filled cyst with characteristic cytological and histopathological features. Interstitial endocrine cell hyperplasia was characterized by abnormal and excessive proliferation of interstitial endocrine cells around the cystic structures. Luteal cysts on gross examination showed thick and opaque walls. Oophoritis revealed focal to diffuse infiltration of inflammatory cells. Additionally, other functional disorders such as embedded corpus luteum, follicular atresia, serous inclusion cysts, folliculoids, polyoogonia, and smooth ovaries are noticed with unique histopathological features. Vascular disturbances were commonly noticed associated with these pathologies. Neoplastic conditions, such as cavernous hemangiomas showed mottled ovary which revealed large, dilated engorged blood vessels histopathologically. Hemangiopericytomas, histopathologically revealed characteristic fingerprint pattern of pericytes. Histiocytomas showed greyish white nodular structures grossly. Large, round cells with irregular borders with few mitotic figures were noticed cytologically and histopathological examination showed proliferation of neoplastic polyhedral histiocytes. Granulosa cell tumors showed radially arranged granulosa cells with centrally located Call Exner body on cytological and histopathological examination. Hemangiosarcomas were characterized by abnormal endothelial cell proliferation both in solid and capillary types.

Thirty five uterine samples were examined which showed 54.3% pathological lesions and other 45.7% were normal. Among 54.3 % the noninflammatory conditions were 31.4% and inflammatory conditions were 22.8%. Inflammatory conditions included acute and chronic endometritis in four cases (14.2%), cystic endometrial hyperplasia- pyometra (CEH-pyometra) complex in three cases (8.5%) and subacute endometritis in one case (2.8%). Noninflammatory conditions included, the non-neoplastic conditions such as uterine adenomyosis in eight cases (22.8%), endometrial glandular hyperplasia in four cases (11.4%), cystic endometrial hyperplasia in three cases (8.5%), mucometra in one case (2.8%), peri glandular fibrosis in two cases (5.7%), endometrial polyps in one case (2.8%), hemosiderosis in thirteen cases (37.4%) and neoplastic lesions included uterine leiomyosarcoma in one case (2.8%), uterine adenoma in two cases (5.7%), endometrial adenocarcinoma in one case (2.8%) and scirrhous adenocarcinoma in one case (2.8%).

Acute and Chronic endometritis exhibited glandular epithelial desquamation, mononuclear cell infiltration, and fibroplasia. CEH-pyometra complex was characterized by significant endometrial thickening with cystic structures filled with inflammatory debris. Non-inflammatory conditions included uterine adenomyosis characterized by dissemination of endometrial glands into myometrium, endometrial glandular hyperplasia with anormal proliferation of endometrial glands in mucosal layer, cystic endometrial hyperplasia characterized by hyperplasia of superficial glands of endometrium, mucometra showed bilateral distended uterine horns due to accumulation of mucoid fluid, periglandular fibrosis as adjoining lesion of chronic endometritis and endometrial adenocarcinoma. Polypoid projections of mucosal layer were noted in endometrial polyps. Neoplastic conditions such as uterine adenoma, uterine leiomyosarcoma, endometrial adenocarcinoma, and scirrhous adenocarcinoma showed distinct histopathological features. Hemosiderosis was observed in association with several uterine pathologies.

The immunohistochemical analysis identified key markers in uterine and ovarian pathologies of domesticated queen cats. Notably, strong cytokeratin expression was observed in epithelial cells of endometrial adenocarcinoma, scirrhous adenocarcinoma and cystic endometrial hyperplasia. Smooth muscle actin (SMA) was expressed in neoplastic muscle cells of uterine leiomyosarcoma. Vimentin showed strong positivity in pericytes of ovarian hemangiopericytoma, while inhibin exhibited immunopositivity in granulosa and interstitial endocrine cells. Vascular endothelial growth factor (VEGF) was detected in stromal blood vessels, indicating its role in angiogenesis. These findings contribute to a better understanding of the molecular aspects of uterine and ovarian disorders in queen cats, enhancing diagnostic accuracy and treatment approaches in veterinary practice.

Finally, the study unveils the complexity of reproductive tract abnormalities in queen cats, emphasizing the prevalence of ovarian and uterine pathologies. It highlights the significance of thorough pathological examination of lesions such as follicular cysts, interstitial endocrine cell hyperplasia, endometritis, CEH-pyometra complex and few neoplastic conditions offering valuable insights and explaining the importance of early spaying in cats. The study also underscores the importance of immunohistochemical markers in characterizing these pathologies. This research was pivotal for enhancing diagnostic accuracy and treatment strategies, ultimately preserving the reproductive health of queen cats and advancing feline veterinary care.