A RETROSPECTIVE STUDY OF NEOPLASIA IN NONDOMESTIC FELIDS IN HUMAN CARE, WITH A COMPARATIVE LITERATURE REVIEW

Fonseca SM, Silva Filho GB, Wicpolt NS, L. Araújo J, Souza DS, Silva MA, Murphy BG, Asin J, Uzal FA, Mendonça FS, Henderson EE. Gingival squamous cell carcinoma in 2 lions under managed care

Neoplasia is one of the main causes of euthanasia in geriatric captive nondomestic felids. However, few studies have examined oral tumors in these animals. We describe here the clinicopathologic features of gingival squamous cell carcinoma (SCC) in 2 lions (Panthera leo) from separate zoologic collections. In both cases, the lions had a history of sialorrhea, bloody oral discharge, and anorexia. Autopsy findings in both lions were similar and were characterized by poorly circumscribed, friable, and bloody gingival masses with grossly apparent invasion of the mandibular bone; a pathologic fracture was observed in 1 case. Histologically, the masses consisted of poorly circumscribed, unencapsulated, densely cellular proliferations of neoplastic epithelial cells arranged in irregular islands, cords, and anastomosing trabeculae with formation of keratin pearls, which, coupled with positive immunohistochemistry for pancytokeratin, were diagnostic for SCC. Although no metastases were found in either animal, both lions were ultimately euthanized because of poor prognosis.

Pulmonary acinar adenocarcinoma in a captive lioness (Panthera leo)

Neoplasms in wild felids are more frequently observed in captive animals, of which clinicopathological features of pulmonary tumors are not commonly described. This study aimed to describe the clinical and pathological aspects of a case of diffuse pulmonary acinar adenocarcinoma in a 23-year-old, captive lioness with clinical history of dyspnea, progressive weight loss and inappetence. At necropsy, the lungs were mildly pale, moderately firm, and the pleural surface was diffusely irregular with multifocal to coalescent, grey to white areas. No masses or superficial nodules were detected, but, on the cut surface, there were numerous, spherical, firm, white to yellow areas up to 0.5 cm in diameter affecting all pulmonary lobes. Histologically, in the lungs, there were extensive, non-delineated areas of neoplastic proliferation of columnar, ciliated epithelial cells arranged in irregular tubuloacinar structures. Immunohistochemical analysis revealed immunolabeling of neoplastic cells for pan-cytokeratin and thyroid transcription factor-1. Napsin-A exhibited only scarce and scattered immunolabeling in the neoplastic cells. The gross, histologic and immunohistochemical findings confirmed the final diagnosis of primary diffuse pulmonary adenocarcinoma.

Spinal disease in a captive population of Panthera species: Review of 86 cases (2003-2021)

This retrospective study aimed to characterize and determine the prevalence of spinal disease in nondomestic felids within a sanctuary population. A review of 304 postmortem examination reports in Panthera species from 2003 to 2021 revealed that 86/304 (28%) were diagnosed with spinal disease. Spinal lesions were categorized according to pathologic process: degenerative (78/86, 91%), developmental (8/86, 9%), inflammatory (6/86, 7%), or neoplastic (8/86, 9%). Degenerative lesions included intervertebral disk disease (IVDD; 66/78, 85%), spondylosis without concurrent IVDD (4/78, 5%), and idiopathic (noncompressive) degenerative myelopathies (8/78, 10%). Fourteen individuals had lesions in more than 1 category. Developmental cases were vertebral (4/8) or spinal cord (3/8) malformations or both (1/8). Inflammatory lesions included meningitis (4/6) and meningomyelitis (2/6). Neoplasia included vertebral multiple myeloma (4/8) and others (4/8). IVDD often involved multiple disks but primarily affected the cervical (41/66, 62%) and thoracic spine (32/66, 48%). A multivariate binary logistic model predicted the diagnosis of IVDD at postmortem examination, where odds of being affected were highest for males, lions (Panthera leo), and geriatric age group (>14 years). The spinal lesions documented in this study provide insight into high-risk signalment categories and predominant associated lesions affecting captive Panthera populations. Specifically, spinal disease, especially cervical IVDD, is common among Panthera species, and lions, males, and older felids are at increased risk.

Use of oral chemotherapeutic agent, chlorambucil, as palliative treatment of thryoid adenocarcinoma in a golden-headed lion tamarin (Leontopithecus chrysomelas)

This case report describes the use of chlorambucil in a 7.5-year-old golden-headed lion tamarin (Leontopithecus chrysomelas) as palliative therapy for thyroid adenocarcinoma. Treatment was initiated at 0.1 mg/kg orally once daily. No physical abnormalities or substantial changes in complete blood cell counts and thyroid hormone levels from serial samples were detected.

MELANOCYTIC NEOPLASIA IN PANTHERA SPECIES: CLINICAL PRESENTATIONS, PATHOLOGIC FINDINGS AND RESPONSES TO TREATMENT

Neoplasia is a common cause of morbidity and mortality in captive nondomestic felids. Seven tigers (Panthera tigris), two African lions (Panthera leo), and two snow leopards (Panthera uncia) were diagnosed with melanocytic neoplasia (10 malignant melanomas, two benign melanocytomas) over a 20-yr period. Animals were 10-19 yr old and 5/7 tigers were phenotypically white. Malignant melanoma tumor location included skin (n = 4), oral mucosa (n = 2), nasal planum (n = 1), iris/uvea (n = 2), and lip margin (n = 1); melanocytomas were found in skin (n = 2). Metastasis to regional lymph nodes was seen at diagnosis in 3/7 melanoma cases. Thoracic radiography (n = 6) and/or computed tomography (n = 2) did not detect pulmonary metastasis at diagnosis but were useful for detection later in the disease course. Median survival time (MST) for all cases ranged from 1 mon - 40 mon. Seven cases with malignant melanoma underwent treatment, which included surgery, radiation therapy, and administration of the canine melanoma vaccine (Oncept^®) or a combination of these treatments; MST was 5-40 mon for these cases. While multimodal therapy may provide an improved survival time, the majority of animals with malignant melanoma invariably died from neoplastic disease. Necropsy confirmed metastasis of malignant melanoma in 7/9 animals; sites included lung, liver, lymph node, kidney, mesentery, pleural cavity, heart, stomach, spleen, and adrenal gland. This case series describes the clinical and histologic findings of melanocytic neoplasia in nondomestic felids as well as multimodal treatment strategies incorporating the canine melanoma vaccine.

Of Elephants and Other Mammals: A Comparative Review of Reproductive Tumors and Potential Impact on Conservation

Reproductive tumors can impact conception, pregnancy, and birth in mammals. These impacts are well documented in humans, while data in other mammals are limited. An urgent need exists to understand the reproductive impact of these lesions in endangered species, because some endangered species have a documented high prevalence of reproductive tumors. This article documents that the prevalence of both benign and malignant neoplasia differs between African and Asian elephants, with Asian elephants more frequently diagnosed and negatively affected by both. The prevalence of these tumors across mammalian species is compared, and impact plus treatment options in human medicine are reviewed to inform decision making in elephants. Evidence suggests that reproductive tumors can negatively impact elephant conservation. Future studies that document reproductive outcomes, including the success of various treatment approaches in elephants with tumors will benefit conservation efforts.