MANDIBULAR SQUAMOUS CELL CARCINOMA IN A BOBCAT (LYNX RUFUS)

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.

An Overview of Neoplasia in Captive Wild Felids in Southern Italy Zoos

The aim of this study was to evaluate the frequency of neoplasms in captive wild felids in Southern Italy zoos over a 13-year period (2008–2021) and to investigate macroscopic and histologic tumor findings in these animals. A total of 24 cases were necropsied, 9 males and 15 females, with age ranging from 6 to 19 years, including 12 tigers (Panthera tigris), 7 leopards (Panthera pardus), 4 lions (Panthera leo), and 1 black jaguar (Panthera onca). Diagnosis of neoplasm was made in 14/24 cases (58.3%). Tumors diagnosed were two cholangiocarcinomas, two hemangiosarcomas of the liver, two uterine leiomyomas, a renal adenocarcinoma, an adrenal gland adenoma, a thyroid carcinoma, an oral squamous cell carcinoma, an osteoma, a meningioma, a mesothelioma, an esophageal leiomyosarcoma, a muscoloskeletal leiomyosarcoma and a thyroid adenoma. The malignant and benign tumors were 62.5 and 37.5%, respectively. Among malignant tumors, no metastasis was observed in 50% of cases; in 10% of cases metastasis involved only regional lymph nodes; and distant metastases were found in 40% of cases. Based on our findings, the liver was the most frequent primary tumor site (25%). The high rates of malignant and widely metastatic neoplasms suggest the importance of active monitoring and management of neoplasia in these threatened and endangered species.

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

This retrospective study of neoplasia in nondomestic felids in human care presents the cases diagnosed at Northwest ZooPath (NWZP), Monroe, Washington, from 1998 to 2017 in conjunction with a scoping literature review. The 554 neoplasms identified in 20 species in the NWZP archive were combined with the 984 neoplasms identified in those same species in the published literature. Some of the cases identified in the literature were from the NWZP archive. Based on this review, mammary adenocarcinoma (183/1,483, 12.3%), lymphoma (89/1,483, 6.0%), squamous cell carcinoma (85/1,483, 5.7%), pheochromocytoma (57/1,483, 3.8%), and thyroid adenoma (57/1,483, 3.8%) are the most frequently reported neoplasms in nondomestic felids in human care. Apparent species predilections for neoplasia include mammary adenocarcinoma in tigers, jaguars, lions, and jungle cats; lymphoma in lions and tigers; squamous cell carcinoma in snow leopards; pheochromocytoma in clouded leopards; ovarian adenocarcinoma in jaguars; cholangiocarcinoma in lions and tigers; multiple myeloma in tigers; bronchoalveolar adenocarcinoma in cougars and lions; hemangiosarcoma, hepatocellular carcinoma, and gastrointestinal adenocarcinoma in lions; mesothelioma in clouded leopards, lions, and tigers; myelolipoma and cutaneous mast cell tumor in cheetahs; soft tissue sarcomas in tigers; and transitional cell carcinoma of the urinary bladder in fishing cats.

Successful treatment of early cutaneous squamous cell carcinoma with hypofractionated radiation therapy in an African lion (Panthera leo)

Cutaneous squamous cell carcinoma (SCC) is a slow growing but locally invasive neoplasm, most commonly caused by prolonged exposure to ultraviolet (UV) radiation. Whilst SCC accounts for 15% of skin tumours in domesticated cats, cutaneous SCC in non-domesticated felids (apart from captive snow leopards) appears to be uncommon, with only three reports in the literature to date. In this report, a captive African lion (Panthera leo) presented with two ulcerative lesions on the nasal planum. Histopathology of the lesions revealed epidermal keratinocyte dysplasia and neoplastic basal- and supra-basal epithelial cells with dyskeratosis and evidence of basement membrane breaching and dermal invasion, consistent with a diagnosis of SCC. There was also evidence of laminar fibrosis and inflammation of the subjacent dermis suggesting that the SCC most likely resulted from UV-induced neoplastic transformation of the epidermal squamous epithelium following actinic keratosis. The lion was treated with hypofractionated radiation therapy and remained in remission until his death (euthanised 17 months later because of age-related chronic renal failure). This is the first report of cutaneous SCC in a lion with evidence of actinic damage and resolution after radiation therapy.

The occurrence of cancer in vertebrates: a mini review

Neoplasia is a multilevel condition caused by irregularities over the genome, which can lead to a fatal result. To fully understand this phenomenon, an evolutionary challenge has risen during the last decades, away from human limits, driving the scientific quest into the wild life. The study of wild vertebrate populations in their natural habitats has shown that cancer is rather prominent. Thus, the diversity of vertebrates reported with some form of neoplasia is quite scattered through a variety of habitats. However, some species constitute exceptions by exhibiting cancer-protective features, driven by certain loci in their DNA. It is obvious that from an evolutionary standpoint, the incidence of cancer in different taxa is nowadays studied by seeking for patterns and their roots. The main purpose of the evolutionary approach is no other than to answer a fundamental question: Could cancer be ultimately regarded as another evolutionary force conducive to the formation or shaping-up of species?

A RETROSPECTIVE STUDY OF MORBIDITY AND MORTALITY IN THE NORTH AMERICAN AMUR LEOPARD ( PANTHERA PARDUS ORIENTALIS) POPULATION IN ZOOLOGIC INSTITUTIONS FROM 1992 TO 2014

The Amur leopard ( Panthera pardus orientalis) is one of the most critically endangered leopards on the International Union for the Conservation of Nature red list. The primary objective of this retrospective study was to identify common and significant causes of morbidity and mortality in the North American Amur leopard zoo population. This information provides insights that contribute to their improved care, health, and medical management and, ultimately, affects the sustainability of this leopard subspecies in the wild. Medical records and complete postmortem reports were requested from all North American zoologic institutions that held Amur leopards in their collections from 1992 to 2014. Information from 175 individuals, representing 93% of the population (188 animals), was received. Data were reviewed generally and by subdivision into the following age groups: neonate: 0 day-3 mo ( n = 45); juvenile-young adult: 3 mo-5 yr ( n = 21); adult: 5-10 yr ( n = 17); senior: 10-15 yr ( n = 31); or geriatric: >15 yr ( n = 61). The major causes of morbidity, listed by body system for the study population, excluding neonates, were musculoskeletal (40%), reproductive (24%), dental (19%), cardiopulmonary (13%), gastrointestinal (13%), and urogenital (12%). The two most common causes of death or euthanasia, primarily in senior and geriatric animals, were chronic renal disease and neoplasia; maternal neglect and maternal trauma were most common in neonates. The largest populations in this study were neonates and geriatrics, indicating that if animals survive the neonatal period, they often live into their late teens to early 20s. This is the first comprehensive study of the causes of morbidity and mortality in the Amur leopard zoo population in North America.

Dental Pathology of the Iberian Lynx (Lynx pardinus), Part II: Periodontal Disease, Tooth Resorption, and Oral Neoplasia

The Iberian lynx is an endangered felid that has been subject to an intensive, ongoing conservation program to save it from extinction. Identification of dental pathologies could play an important role in the survival of this endangered species. The prevalence of periodontal bone loss, tooth resorption, and oral neoplasia was evaluated in this species. Skulls of 88 adult specimens of the Iberian lynx ( Lynx pardinus) from the Doñana Biological Station (EBD-CSIC), Seville, Spain, were examined macroscopically and full-mouth dental radiographs of all specimens were performed. Different stages of periodontal disease were identified in 81.3% of teeth. Approximately two-thirds (64.8%) of the specimens examined had at least 1 tooth affected by stage 3 or 4 periodontal disease. Maxillary and mandibular incisor teeth accounted for a majority (59.4%) of teeth affected by stage 3 or 4 periodontal disease. Tooth resorption affected 12 teeth (0.63% of evaluated teeth) in 6 skull specimens (6.8% of skulls evaluated). Five of the teeth with resorptive lesions were detected on 1 skull specimen. Six teeth (50%) of those affected by tooth resorption were incisor teeth. Only 1 (1.1%) adult specimen showed signs of oral neoplasia. Our study concluded that there is a high prevalence of periodontal disease that could lead to impaired hunting ability, as well as may represent a threat to overall health and subsequent survival of this endangered species. The extremely low prevalence of tooth resorption in L pardinus could open new pathways in the discovery on the pathogenesis of tooth resorption in felids.

Tongue Squamous Cell Carcinoma in a European Lynx (Lynx Lynx): Papillomavirus Infection and Histologic Analysis

Oral squamous cell carcinoma (SCC) is a common finding in domestic and wild felids. Only two cases of oral SCC have been reported in Lynx species (Lynx rufus and Lynx canadensis), at mandibular and gingival sites. In this study, we describe the first report of tongue SCC in a 15 years old female European lynx (Lynx lynx), along with viral investigations. Necropsy and histological analysis were performed and the presence of papillomavirus (PV) infection was investigated by ultrastructural and molecular methods. The lardaceous mass at tongue level was histologically diagnosed as moderately differentiated SCC. Typical microscopical features of SCC were also found in the retropharyngeal lymph node and at the pulmonary level. Neither viral DNA by PCR, nor viral particles by transmission electron microscopy were found. Despite that PV infection is associated with Felidae, this work reports the first description of tongue SCC in Lynx species, but no evidence of PV infection, suggesting that PV may not be involved in development of SCC in bobcat species.

Oral Squamous Cell Carcinoma in Three Related Kowari (Dasyuroides byrnei)

We report three kowari (Dasyuroides byrnei) with squamous cell carcinoma affecting the gingiva. These cases occurred in rapid succession in a related group of individuals of similar age, suggesting a familial tendency to this condition and a typical age of presentation. Other conditions affecting the oral cavity can mimic the appearance of oral squamous cell carcinoma in this species, and so knowledge of this condition can assist the veterinarian in making rapid decisions regarding prognosis and improving the welfare of these animals.