Epithelioid mesothelioma in a Crab-eating Fox - Cerdocyon thous (Linnaeus, 1766)

Epithelioid mesothelioma in a Crab-eating Fox - Cerdocyon thous (Linnaeus, 1766) | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report Epithelioid mesothelioma in a Crab-eating Fox - Cerdocyon thous (Linnaeus, 1766) Osvaldo Lírio Corrêa, Thais Oliveira Morgado, João Paulo Silva Cavasani, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6455256/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Mesothelioma is a malignant neoplasm considered rare, which has a mesothelial origin, affecting the cells that line body cavities and can affect humans, domestic animals and wild animals. In wild canids, it proves to be a rare find. The objective of the present study is to describe the macroscopic, histopathological and immunohistochemical aspects of a case of epithelioid mesothelioma in Cerdocyon thous, female, aged approximately 14 years and resident at the Center for Medicine and Research in Wild Animals of the Federal University of Mato Grosso. The individual presented with a severe clinical condition and rapid progression of signs. Despite the immediate start of supportive treatment, the animal died on the same day, being sent for necropsy. Macroscopically, multiple irregular, firm, reddish-white masses were observed in the omentum. In the histopathological analysis, it consisted of proliferation of neoplastic cells with a solid pattern, where the cells were predominantly rounded, with a slightly eosinophilic and normally broad cytoplasm, with a rounded, broad, normally vacuolated, basophilic and sometimes multiple nucleus. Anisocytosis and anisocariosis with mild to moderate intensity and mild cellular pleomorphism were also present. In addition, two to eight mitosis figures were observed in the field of higher magnification. The neoplastic population was supported by a delicate stroma of connective tissue that was sometimes thick and formed delicate septa. With this, the occurrence and first report of epithelioid mesothelioma in Cerdocyon thous is confirmed, contributing to the knowledge and description of a malignant neoplasm in a wild canid. Neoplasm captivity canids wild animals histopathological Figures Figure 1 Figure 2 Figure 3 Introduction Mesothelioma is a malignant neoplasm considered rare, which has a mesothelial origin, affecting the cells that line body cavities, such as the peritoneum and pleura, and is characterized by the formation of masses that may have a unifocal or multifocal distribution or even involve mesothelial lining cells in a continuous manner (Wilson 2002; Zachary 2018). The development of this neoplasm in wild animals may be associated with multiple factors, including genetic predisposition, exposure to environmental carcinogens, and advanced age (Colombino et al., 2019). In humans, the main cause of this tumor is the inhalation of asbestos fibers, and there is evidence that exposure to this and other environmental contaminants may also be related to the occurrence of asbestos fibers in animals (Frank and Joshi, 2014). In addition, individuals kept in captivity may be more susceptible to the development of tumors due to prolonged exposure to urban pollutants and lower genetic variability, factors already associated with the incidence of cancer in wild species (McAloose and Newton, 2009; Vittecoq et al., 2013). Mesothelioma is usually chronic and silent, making early diagnosis difficult and leading to its detection only in advanced stages of the disease (Tsao et al. 2009). It can affect humans (Tsao et al. 2009) and domestic animals, such as cattle, horses, canines and felines (Brown et al. 2007). In wild animals, it has been described in several species belonging to various taxonomic groups, such as Philippine Spotted Deer ( Cervus alfredi ) (Bazin et al. 2022), Four-toed Hedgehog ( Atelerix albiventris ) (Troncoso et al. 2024), Striped Skunk ( Mephitis mephitis ) (Kim et al. 2016), California sea lion ( Zalophus californianus ) (Takami et al. 2023) and in a wild pig (Colombino et al. 2019). In wild felids the number of reports is more significant, with descriptions being found in Bengal tigers ( Panthera tigris ) (Shin et al. 1998; Wiedner et al. 2008; D'Aquino et al. 2022), lions ( Panthera leo ) (Bollo et al. 2011; Rocha et al. 2019), Cheetah ( Acinonyx jubatus ) (Whiton et al. 2013) and jaguars ( Panthera onca ) (Souza et al. 2013; Teixeira et al. 2022), which may suggest that in certain taxonomic groups, this neoplasm is possibly more frequent. However, in canids it proves to be a rare finding, having been found only one report in the literature, in an individual of African Wild Dog ( Lycaon pictus ) kept in a zoo in Philadelphia, United States, affecting the pleura (Stewart 1966) and there is no knowledge of its occurrence in Cerdocyon thous . The latter is a wild canid widely distributed in South America and currently does not present a risk of extinction, having its conservation status classified as of least concern by the International Union for Conservation of Nature (IUCN 2024). It inhabits open areas, fields and savannahs, is medium-sized and omnivorous (Bueno and Motta 2004; Juarez and Marinho-Filho 2002). In view of this, this is the first report in the species and demonstrates the importance of its description in wild canids. Case Report An individual of Cerdocyon thous , female, non-castrated, aged approximately fourteen years and resident at the Center for Medicine and Research in Wild Animals (CEMPAS) of the Federal University of Mato Grosso (UFMT), located in the urban area of the municipality of Cuiabá in the state of Mato Grosso, Brazil, presented with apathy, anorexia and prostration, with rapid evolution and worsening of the clinical condition, showing itself unable to keep up with station. Due to this, he was contained in his enclosure and referred to outpatient clinical care. Physical examination revealed cachexia, intense dehydration, pale mucous membranes, ocular discharge, reddish lesion on the right lower lip, presence of blood in the oral cavity and nostrils, dental alterations such as wear and fractures, in addition to onychogryphosis. Supportive treatment was initiated in order to stabilize the clinical condition, and he was later referred for complementary tests. Thus, the animal remained under follow-up and fluid therapy, analgesia, anti-inflammatory, antibiotic therapy and vitamin supplement were administered. However, the animal died on the same day, and there was no time to carry out complementary diagnostic tests. In view of the clinical picture presented, leishmaniasis was initially suspected, without ruling out the possibility of other diseases, due to the presence of nonspecific clinical signs, of a chronic nature, added to the advanced age of the individual. The animal was sent to the Veterinary Pathology Laboratory (LPV) of UFMT for necropsy. Macroscopically, Cerdocyon thous had a body score of 2 (on a scale of 1, representing cachexia to 5, compatible with an obese animal) (Fig. 1) and moderately pale ocular and oral mucous membranes. In the oral mucosa and gingiva, multifocal to coalescent, rounded to irregular, dark red areas were observed. The pelvic and thoracic limbs showed exacerbated growth and diffuse thickening of the nails (onychogryphosis). All organs were collected and fixed in 10% formaldehyde and, after fixation, they were cleaved, embedded in paraffin, cut to 5μm, stained with hematoxylin and eosin, and analyzed under light microscopy. Samples of peritoneal nodules were also submitted to immunohistochemical analysis, using anti-vimentin and anti-cytokeratin antibodies for better identification and differentiation of the neoplasm. In the subcutaneous tissue, translucent gelatinous content was observed in the ventrocervical region, compatible with edema. In the abdominal cavity, replacing the omentum, multiple irregular, firm, white to light red masses were observed, which, at cut, presented the same pattern and texture (Fig. 2). Other organs did not present macroscopic alterations. Microscopically, the sections of the stomach and omentum were histologically examined. Extending from the serosa of the stomach and omentum is a poorly demarcated, non-encapsulated, and highly cellular population of neoplastic mesothelial cells forming papillary and micropapillary projections, supported by a thin fibrovascular stroma. Neoplastic cells are pleomorphic, rounded, polygonal to spindle-shaped, with variably distinct cell borders, a moderate amount of eosinophilic cytoplasm, slightly vacuolated, round to ovoid central nuclei, vesicular to dotted chromatin, and 1-3 nucleoli. There is moderate anisocytosis and anisocariosis and numerous multinucleated cells (up to 4 nuclei of varying size) with evidence of nuclear molding. The mitotic rate is 2 per 40X magnification field. Scattered neoplastic cells are hypereosinophilic, shrunken, and have pycnotic nuclei (necrosis). Occasionally, there are small aggregates of lymphocytes and rare neutrophils scattered among neoplastic cells. Therefore, sections of the masses found in the omentum were submitted to immunohistochemical analysis with anti-vimentin antibodies using a commercial immunohistochemical kit. Thus, the morphological diagnosis of omentum in this individual with Cerdocyon thous was compatible with epithelioid mesothelioma. Discussion and Conclusions Epithelioid mesothelioma is a rare malignant neoplasm originating from mesothelial cells that line serous cavities, such as the pleura, peritoneum, and pericardium (Wilson & Dungworth, 2002; Zachary, 2018). This tumor often presents aggressive behavior, being highly infiltrative, disseminating by contact and frequently affecting multiple organs, due to transcolomic propagation, in which neoplastic cells detach and spread through the serous fluid of the cavities (Tsao et al., 2009). Epithelioid mesothelioma is characterized by an expansive and invasive growth, which can be of silent and prolonged evolution, chronic in character, and often leads to late clinical manifestations, including cavitary effusions and nonspecific signs, such as weight loss and apathy (Brown et al. 2007; Souza et al. 2013). In the present case, the mesothelioma presented with multiple firm and white masses in the omentum, a typical location for the tumor, and was associated with cachexia, prostration and rapid worsening of the animal's general condition, which is in line with what has been described in the literature. The presence of necrosis and mononuclear inflammatory infiltration observed in the histopathological examination reiterates its aggressive character and the advanced progression of the disease (Vittecoq et al. 2013; McAloose and Newton 2009). Mesothelioma has been described in several species of wild animals, both in an environment under human care and in the wild, although there is a greater number of reports in individuals kept under human care, suggesting a possible relationship with environmental factors, such as exposure to contaminants and reduced genetic diversity in captivity (Wiedner et al. 2008; Bollo et al. 2011; Souza et al. 2013; D'Aquino et al. 2022). In wild felids there is a considerable number of descriptions of mesotheliomas, in several species as mentioned above, however, it is also noteworthy that the reports are from different countries, such as South Korea, Italy, Germany, Brazil and the United States (Shin et al. 1998, Wiedner et al. 2008; Bollo et al. 2011; Souza et al. 2013; Whiton et al. 2013; Junginger et al. 2015; Rocha et al. 2019; D'Aquino et al. 2022, Teixeira et al. 2022), demonstrating that, in addition to possibly being more frequent in wild felids, it has a wide geographical distribution worldwide. In cervids, mesothelioma was diagnosed in a Cervus alfredi in Germany, kept under human care, reinforcing the hypothesis of a predisposition in captive animals (Bazin et al., 2022). The tumor has also been reported in a free-living wild pig in Italy, with peritoneal involvement, reinforcing its infiltrative and disseminative nature (Colombino et al. 2019). In addition, a recent case documented pleural mesothelioma in a Zalophus californianus kept under human care in an aquarium in Japan, showing that the tumor can also affect marine mammals (Takami et al. 2023). In all these reports, the disease presented a chronic character, with nonspecific clinical signs such as cachexia, cavitary effusions and lethargy, and was often diagnosed only at necropsy, bringing points in common to the picture presented by the individual with Cerdocyon thous in the present report. Regarding mesothelioma in wild canids, significant similarities can be seen between the present report and the case reported by Stewart (1966) in an Lycaon pictus kept in a zoo in Philadelphia, United States. In both cases, the tumor presented an infiltrative and disseminative character, extensively affecting the serous of the body cavities. In Lycaon pictus , the neoplasm was identified in the pleura, resulting in multiple irregular masses associated with thoracic effusion, a pattern similar to that observed in the present report, in which the neoplasm diffusely affected the omentum, forming firm and white-haired masses. In addition, in both cases, histopathology revealed neoplastic cells organized predominantly in a solid pattern, with eosinophilic cytoplasm and vacuolated nucleus, in addition to occasional mitosis, reflecting aggressive behavior. Another point in common is that both individuals were kept under human care, raising the hypothesis that environmental factors and exposure to possible carcinogenic agents may be involved in the pathogenesis of the disease. This is the first report of epithelioid mesothelioma affecting the omentum in an individual of Cerdocyon thous , contributing to the knowledge and description of a malignant neoplasm in a wild canid of the Brazilian fauna. These findings reinforce the need for additional studies on the occurrence of mesotheliomas in wild animals and their possible correlation with the captive environment, since environmental factors may play a role in carcinogenesis and should be considered in the sanitary and epidemiological surveillance of these animals. Declarations The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. The authors have no relevant financial or non-financial interests to disclose. All authors contributed to the conception and design of the study. The initial care of the patient was performed by Sandra Helena Ramiro Corrêa, the exams were performed by João Paulo da Silva Cavasani and Caroline Argenta Pescador, the data collection was performed by Osvaldo Lírio Corrêa and Thais Oliveira Morgado. The first version of the manuscript was written by Osvaldo Lírio Corrêa and all authors commented on the previous versions of the manuscript. All authors have read and approved the final manuscript. Ethics approval This study was developed with data from the medical records of an animal treated in the hospital routine of the Wild Animals Sector of the Federal University of Mato Grosso (UFMT) and from the report of the Veterinary Pathology Laboratory of UFMT. The animal died spontaneously and therefore did not have a registration number in Ethics Committee - Use of Animals (CEUA) - UFMT. References Bazin M, Schwinn J, Kühl B, Armando F, Beineke A (2022). Malignant epithelioid mesothelioma in a Visayan spotted deer ( Cervus alfredi ). Berl und Münch Tierärztl Wochenschr, 135. http://dx.doi.org/10.2376/1439-0299-2021-28 Bollo E, Scaglione FE, Tursi M, Schröder C, Degiorgi G, Belluso E, Capella S, Bellis D (2011) Malignant pleural mesothelioma in a female Lion ( Panthera leo ). Res Vet Sci. 91:116–8. https://doi.org/10.1016/j.rvsc.2010.08.005 Brown CC, Baker DC, Barker IK (2007) Alimentary system. In: Jubb K, Palmer’s (ed) Pathology of domestic animals, 5 ed. Elsevier, New York, pp. 294–296 Bueno AD, Motta JC (2004). Food habits of two syntopic canids, the maned wolf ( Chrysocyon brachyurus ) and the crab-eating fox ( Cerdocyon thous ), in southeastern Brazil. Rev Chil de Historia Nat, 77: 5-14. Colombino E, Capella S, Casalinuovo F, Racco R, Pruiti F, Volante M, Lo Presti VDM, Belluso E, Capucchio MT (2019). Malignant peritoneal mesothelioma in a boar who lived in Calabria (Italy): Wild animal as sentinel system of human health. Sci of the Total Environ, 683: 267-274. https://doi.org/10.1016/j.scitotenv.2019.05.254 D'Aquino I, Piegari G, Casciaro SM, Prisco F, Rosato G, Silvestre P, Uberti BD, Capasso M, Laricchiuta P, Paciello O, Russo V (2022). An overview of neoplasia in captive wild felids in southern Italy zoos. Front in Vet Sci, 9. https://doi.org/10.3389/fvets.2022.899481 Frank AL, Joshi TK (2014) The global spread of asbestos. Annals of global health, 80(4): 257-262. https://doi.org/10.1016/j.aogh.2014.09.016 IUCN (2024) The IUCN Red List of Threatened species. International Union for Conservation of Nature’s. https://www.iucnredlist.org/species/4248/81266293. Acesso em 15 de outubro de 2024. Juarez KM, Marinho-Filho J (2002). Diet, habitat use, and home ranges of sympatric canids in Central Brazil. J of Mammal, 83: 925-933. https://doi.org/10.1644/1545-1542(2002)0832.0.CO;2 Junginger J, Hansmann F, Herder V, Lehmbecker A, Peters M, Beyerbach M, Wohlsein P, Baumgärtner W (2015). Pathology in captive wild felids at German zoological gardens. PLoS One, 10(6). https://doi.org/10.1371/journal.pone.0130573 Kim SM, Oh Y, Oh SH, Han JH (2016). Primary diffuse malignant peritoneal mesothelioma in a striped skunk ( Mephitis mephitis ). J of Vet Med Sci, 78(3): 485-487. https://doi.org/10.1292/jvms.15-0377 McAloose D, Newton AL (2009) Wildlife cancer: a conservation perspective. Nat rev cancer, 9(7): 517-526. https://doi.org/10.1038/nrc2665 Rocha PRD, Duarte RP, Laranjeira MG, Melo TAL, Azevedo EZ, Garcia SD, Machado GF (2019) Hemotórax fatal causado por mesotelioma pleural em um leão. Pesqui Vet Bras, 39, 416-418. https://10.1590/1678-5150-PVB-6184. Shin NS, Kwon SW, Kim DY, Kweon OK, Seo IB, Kim JH (1998). Metastatic malignant mesothelioma in a tiger ( Panthera tigris ). J of Zoo and Wildl Med, 81-83. Souza FDAL, de Carvalho CJS, de Almeida HM, Pires LV, dos Santos Silva L, Costa FAL, de Sousa Silva SMM (2013). Peritoneal mesothelioma in a jaguar ( Panthera onca ). J of Zoo and Wildl Med, 44(3): 737-739. https://doi.org/10.1638/2010-0122R5.1 Stewart HL (1966). Pulmonary cancer and adenomatosis in captive wild mammals and birds from the Philadelphia Zoo. J of the Natl Cancer Inst, 36(1): 117-138. Takami Y, Tanaka M, Morita M, Maruno T, Anai N, Sudo T, Kezuka C, Izawa T, Yamate J, Kuwamura M. (2023). Pleural mesothelioma in a California sea lion ( Zalophus californianus ). J of Vet Med Sci, 85(9), 1030-1033. https://doi.org/10.1292/jvms.22-0457 Teixeira RH, Caiaffa MG, Silva ML, Silveira JP, Nemer VC, Costa ALMD (2022). Mesotelioma peritoneal em onça-pintada ( Panthera onca Linnaeus, 1758). Clín Vet, 27(158), 22-32. Troncoso I, Brown J, Isla C, Lajara JM, Ebner M, Fehrmann-Cartes K (2024). Case report: Abdominal mesothelioma in Atelerix albiventris . Front in Vet Sci, 11: 1341815. https://doi.org/10.3389/fvets.2024.1341815 Tsao AS, Wistuba I, Roth JA, Kindler HL (2009) Malignant pleural mesothelioma. J of Clin Oncol, 27(12): 2081-2090. https://doi.org/10.1200/JCO.2008.19.8523 Wiedner EB, Isaza R, Lindsay WA, Case AL, Decker J, Roberts J (2008). Pericardial mesothelioma in a Bengal tiger ( Panthera tigris ). J of Zoo and Wildl Med, 39(1): 121-123. https://doi.org/10.1638/2007-0080.1 Wilson DW, Dungworth DL (2002) Tumors of the respiratory tract. In: Meuten D J (ed) Tumors in Domestic Animals, 4 ed. Iowa State Press, Ames, pp 398-399 Whiton A, Schumacher J, Evans EE, Novak JM, Crews A, Ramsay E, Donnell R (2013). Mesothelioma in two nondomestic felids: North American cougar ( Felis concolor ) and cheetah ( Acinonyx jubatus ). Case Rep in Vet Med, 1: 286793. https://doi.org/10.1155/2013/286793 Zachary JF (2018) Bases da Patologia em Veterinária. Elsevier, Rio de janeiro. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6455256","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":463836676,"identity":"89c1f3a8-8eda-44c4-b8c3-6aae47586c7d","order_by":0,"name":"Osvaldo Lírio Corrêa","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBklEQVRIiWNgGAWjYLCCB2wMzGBGgoGNHIg+8ICQlgSYlg8VacZgLQlEaAEDxhlnDic2gEXwqObnP2P4IaHMhh3IMP7M25aWPj/s8EOgLXZyug3YtUjOyDGWSDiXxgxkmEnzttnkbrydZgDUkmxsdgC7FoMbbAkSiW2HmQ1u8JgxA23J3Tg7AaTlQOI2XFrOH0v+AdJifx7ssMPphrPTP+DXciD5GMQWhhwDSaD3E+Slc/DbIjkj+ZgFyC8SN9LKJICBbLhBOqfgQIIBbr/w8x9svvGhzCaZv//w5g/AqJSXn52++cOHCjs5XFpgIBnJqWASv3IQsIOz5BsIqx4Fo2AUjIKRBQAlEmNpt0bq1AAAAABJRU5ErkJggg==","orcid":"","institution":"Hospital Veterinário, Universidade Federal de Mato Grosso (HOVET/UFMT)","correspondingAuthor":true,"prefix":"","firstName":"Osvaldo","middleName":"Lírio","lastName":"Corrêa","suffix":""},{"id":463836677,"identity":"944fff3a-c6b2-4537-9568-7e02c7d4adf7","order_by":1,"name":"Thais Oliveira Morgado","email":"","orcid":"","institution":"Hospital Veterinário, Universidade Federal de Mato Grosso (HOVET/UFMT)","correspondingAuthor":false,"prefix":"","firstName":"Thais","middleName":"Oliveira","lastName":"Morgado","suffix":""},{"id":463836678,"identity":"31a5736b-d7ef-4d1f-a1aa-7b0b375eec2f","order_by":2,"name":"João Paulo Silva Cavasani","email":"","orcid":"","institution":"Hospital Veterinário, Universidade Federal de Mato Grosso (HOVET/UFMT)","correspondingAuthor":false,"prefix":"","firstName":"João","middleName":"Paulo Silva","lastName":"Cavasani","suffix":""},{"id":463836679,"identity":"a841313a-fce3-4453-9b72-91c7633dcba3","order_by":3,"name":"Caroline Argenta Pescador","email":"","orcid":"","institution":"Hospital Veterinário, Universidade Federal de Mato Grosso (HOVET/UFMT)","correspondingAuthor":false,"prefix":"","firstName":"Caroline","middleName":"Argenta","lastName":"Pescador","suffix":""},{"id":463836680,"identity":"32bb2c72-e928-4c20-9611-53aa64b3a004","order_by":4,"name":"Sandra Helena Ramiro Corrêa","email":"","orcid":"","institution":"Hospital Veterinário, Universidade Federal de Mato Grosso (HOVET/UFMT)","correspondingAuthor":false,"prefix":"","firstName":"Sandra","middleName":"Helena Ramiro","lastName":"Corrêa","suffix":""}],"badges":[],"createdAt":"2025-04-15 13:23:25","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6455256/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6455256/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":83816081,"identity":"47f10035-64b5-41a0-8aeb-e59f9a11e84f","added_by":"auto","created_at":"2025-06-03 07:45:28","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":850194,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eCerdocyon thous\u003c/em\u003e. Note body condition score 2 as well as onychogryphosis\u003c/p\u003e","description":"","filename":"Fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6455256/v1/4f208c0d7a3d6bacea3c8267.jpg"},{"id":83816082,"identity":"385a9775-af47-48e8-bef3-3da5474e8d00","added_by":"auto","created_at":"2025-06-03 07:45:28","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":825100,"visible":true,"origin":"","legend":"\u003cp\u003eOmentum of \u003cem\u003eCerdocyon thous\u003c/em\u003e. Presence of multiple, irregular, firm, white-to-light-red masses\u003c/p\u003e","description":"","filename":"Fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6455256/v1/1686baf03a93b237129d1d39.jpg"},{"id":83816083,"identity":"d25d3793-88d2-4792-9939-17baf1eabad1","added_by":"auto","created_at":"2025-06-03 07:45:28","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":211263,"visible":true,"origin":"","legend":"\u003cp\u003eMesothelioma in \u003cem\u003eCerdocyon thous\u003c/em\u003e. \u003cstrong\u003ea\u003c/strong\u003e. Intercostal muscle. A group of round cells containing moderate cellular pleomorphism characterized by anisocariosis and evident nucleoli is observed. The cytoplasm is moderate and mildly eosinophilic. HE, 20x Bar = 50mm. \u003cstrong\u003eb\u003c/strong\u003e. Positive immunohistochemistry for cytokeratin in session of epithelioid mesothelioma in the omentum, 10x magnification\u003c/p\u003e","description":"","filename":"Fig3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6455256/v1/a51a92c2ffd5e945ffed4b1c.jpg"},{"id":109455987,"identity":"dc915b28-2f74-4ce6-ba46-6960e90df8c1","added_by":"auto","created_at":"2026-05-18 09:55:39","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2022810,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6455256/v1/acbb724f-d5cd-43c1-8497-08afbe98f160.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Epithelioid mesothelioma in a Crab-eating Fox - Cerdocyon thous (Linnaeus, 1766)","fulltext":[{"header":"Introduction","content":"\u003cp\u003eMesothelioma is a malignant neoplasm considered rare, which has a mesothelial origin, affecting the cells that line body cavities, such as the peritoneum and pleura, and is characterized by the formation of masses that may have a unifocal or multifocal distribution or even involve mesothelial lining cells in a continuous manner (Wilson 2002; Zachary 2018).\u003c/p\u003e\n\u003cp\u003eThe development of this neoplasm in wild animals may be associated with multiple factors, including genetic predisposition, exposure to environmental carcinogens, and advanced age (Colombino et al., 2019). In humans, the main cause of this tumor is the inhalation of asbestos fibers, and there is evidence that exposure to this and other environmental contaminants may also be related to the occurrence of asbestos fibers in animals (Frank and Joshi, 2014). In addition, individuals kept in captivity may be more susceptible to the development of tumors due to prolonged exposure to urban pollutants and lower genetic variability, factors already associated with the incidence of cancer in wild species (McAloose and Newton, 2009; Vittecoq et al., 2013).\u003c/p\u003e\n\u003cp\u003eMesothelioma is usually chronic and silent, making early diagnosis difficult and leading to its detection only in advanced stages of the disease (Tsao et al. 2009). It can affect humans (Tsao et al. 2009) and domestic animals, such as cattle, horses, canines and felines (Brown et al. 2007). In wild animals, it has been described in several species belonging to various taxonomic groups, such as Philippine Spotted Deer (\u003cem\u003eCervus alfredi\u003c/em\u003e) (Bazin et al. 2022), Four-toed Hedgehog (\u003cem\u003eAtelerix albiventris\u003c/em\u003e) (Troncoso et al. 2024), Striped Skunk (\u003cem\u003eMephitis mephitis\u003c/em\u003e) (Kim et al. 2016), California sea lion (\u003cem\u003eZalophus californianus\u003c/em\u003e) (Takami et al. 2023) and in a wild pig (Colombino et al. 2019).\u003c/p\u003e\n\u003cp\u003eIn wild felids the number of reports is more significant, with descriptions being found in Bengal tigers (\u003cem\u003ePanthera tigris\u003c/em\u003e) (Shin et al. 1998; Wiedner et al. 2008; D'Aquino et al. 2022), lions (\u003cem\u003ePanthera leo\u003c/em\u003e) (Bollo et al. 2011; Rocha et al. 2019), Cheetah (\u003cem\u003eAcinonyx jubatus\u003c/em\u003e) (Whiton et al. 2013) and jaguars (\u003cem\u003ePanthera onca\u003c/em\u003e) (Souza et al. 2013; Teixeira et al. 2022), which may suggest that in certain taxonomic groups, this neoplasm is possibly more frequent. However, in canids it proves to be a rare finding, having been found only one report in the literature, in an individual of African Wild Dog (\u003cem\u003eLycaon pictus\u003c/em\u003e) kept in a zoo in Philadelphia, United States, affecting the pleura (Stewart 1966) and there is no knowledge of its occurrence in \u003cem\u003eCerdocyon thous\u003c/em\u003e. The latter is a wild canid widely distributed in South America and currently does not present a risk of extinction, having its conservation status classified as of least concern by the International Union for Conservation of Nature (IUCN 2024). It inhabits open areas, fields and savannahs, is medium-sized and omnivorous (Bueno and Motta 2004; Juarez and Marinho-Filho 2002). In view of this, this is the first report in the species and demonstrates the importance of its description in wild canids.\u003c/p\u003e"},{"header":"Case Report","content":"\u003cp\u003eAn individual of \u003cem\u003eCerdocyon thous\u003c/em\u003e, female, non-castrated, aged approximately fourteen years and resident at the Center for Medicine and Research in Wild Animals (CEMPAS) of the Federal University of Mato Grosso (UFMT), located in the urban area of the municipality of Cuiab\u0026aacute; in the state of Mato Grosso, Brazil, presented with apathy, anorexia and prostration, with rapid evolution and worsening of the clinical condition, \u0026nbsp;showing itself unable to keep up with station. Due to this, he was contained in his enclosure and referred to outpatient clinical care. Physical examination revealed cachexia, intense dehydration, pale mucous membranes, ocular discharge, reddish lesion on the right lower lip, presence of blood in the oral cavity and nostrils, dental alterations such as wear and fractures, in addition to onychogryphosis.\u003c/p\u003e\n\u003cp\u003eSupportive treatment was initiated in order to stabilize the clinical condition, and he was later referred for complementary tests. Thus, the animal remained under follow-up and fluid therapy, analgesia, anti-inflammatory, antibiotic therapy and vitamin supplement were administered. However, the animal died on the same day, and there was no time to carry out complementary diagnostic tests. In view of the clinical picture presented, leishmaniasis was initially suspected, without ruling out the possibility of other diseases, due to the presence of nonspecific clinical signs, of a chronic nature, added to the advanced age of the individual. The animal was sent to the Veterinary Pathology Laboratory (LPV) of UFMT for necropsy.\u003c/p\u003e\n\u003cp\u003eMacroscopically, \u003cem\u003eCerdocyon thous\u003c/em\u003e had a body score of 2 (on a scale of 1, representing cachexia to 5, compatible with an obese animal) (Fig. 1) and moderately pale ocular and oral mucous membranes. In the oral mucosa and gingiva, multifocal to coalescent, rounded to irregular, dark red areas were observed. The pelvic and thoracic limbs showed exacerbated growth and diffuse thickening of the nails (onychogryphosis). All organs were collected and fixed in 10% formaldehyde and, after fixation, they were cleaved, embedded in paraffin, cut to 5\u0026mu;m, stained with hematoxylin and eosin, and analyzed under light microscopy. Samples of peritoneal nodules were also submitted to immunohistochemical analysis, using anti-vimentin and anti-cytokeratin antibodies for better identification and differentiation of the neoplasm.\u003c/p\u003e\n\u003cp\u003eIn the subcutaneous tissue, translucent gelatinous content was observed in the ventrocervical region, compatible with edema. In the abdominal cavity, replacing the omentum, multiple irregular, firm, white to light red masses were observed, which, at cut, presented the same pattern and texture (Fig. 2). Other organs did not present macroscopic alterations.\u003c/p\u003e\n\u003cp\u003eMicroscopically, the sections of the stomach and omentum were histologically examined. Extending from the serosa of the stomach and omentum is a poorly demarcated, non-encapsulated, and highly cellular population of neoplastic mesothelial cells forming papillary and micropapillary projections, supported by a thin fibrovascular stroma. Neoplastic cells are pleomorphic, rounded, polygonal to spindle-shaped, with variably distinct cell borders, a moderate amount of eosinophilic cytoplasm, slightly vacuolated, round to ovoid central nuclei, vesicular to dotted chromatin, and 1-3 nucleoli. There is moderate anisocytosis and anisocariosis and numerous multinucleated cells (up to 4 nuclei of varying size) with evidence of nuclear molding. The mitotic rate is 2 per 40X magnification field. Scattered neoplastic cells are hypereosinophilic, shrunken, and have pycnotic nuclei (necrosis). Occasionally, there are small aggregates of lymphocytes and rare neutrophils scattered among neoplastic cells. Therefore, sections of the masses found in the omentum were submitted to immunohistochemical analysis with anti-vimentin antibodies using a commercial immunohistochemical kit. Thus, the morphological diagnosis of omentum in this individual with \u003cem\u003eCerdocyon thous\u003c/em\u003e was compatible with epithelioid mesothelioma.\u003c/p\u003e"},{"header":"Discussion and Conclusions","content":"\u003cp\u003eEpithelioid mesothelioma is a rare malignant neoplasm originating from mesothelial cells that line serous cavities, such as the pleura, peritoneum, and pericardium (Wilson \u0026amp; Dungworth, 2002; Zachary, 2018). This tumor often presents aggressive behavior, being highly infiltrative, disseminating by contact and frequently affecting multiple organs, due to transcolomic propagation, in which neoplastic cells detach and spread through the serous fluid of the cavities (Tsao et al., 2009).\u003c/p\u003e\n\u003cp\u003eEpithelioid mesothelioma is characterized by an expansive and invasive growth, which can be of silent and prolonged evolution, chronic in character, and often leads to late clinical manifestations, including cavitary effusions and nonspecific signs, such as weight loss and apathy (Brown et al. 2007; Souza et al. 2013). In the present case, the mesothelioma presented with multiple firm and white masses in the omentum, a typical location for the tumor, and was associated with cachexia, prostration and rapid worsening of the animal's general condition, which is in line with what has been described in the literature. The presence of necrosis and mononuclear inflammatory infiltration observed in the histopathological examination reiterates its aggressive character and the advanced progression of the disease (Vittecoq et al. 2013; McAloose and Newton 2009).\u003c/p\u003e\n\u003cp\u003eMesothelioma has been described in several species of wild animals, both in an environment under human care and in the wild, although there is a greater number of reports in individuals kept under human care, suggesting a possible relationship with environmental factors, such as exposure to contaminants and reduced genetic diversity in captivity (Wiedner et al. 2008; Bollo et al. 2011; Souza et al. 2013; D'Aquino et al. 2022).\u003c/p\u003e\n\u003cp\u003eIn wild felids there is a considerable number of descriptions of mesotheliomas, in several species as mentioned above, however, it is also noteworthy that the reports are from different countries, such as South Korea, Italy, Germany, Brazil and the United States (Shin et al. 1998, Wiedner et al. 2008; Bollo et al. 2011; Souza et al. 2013; Whiton et al. 2013; Junginger et al. 2015; Rocha et al. 2019; D'Aquino et al. 2022, Teixeira et al. 2022), demonstrating that, in addition to possibly being more frequent in wild felids, it has a wide geographical distribution worldwide.\u003c/p\u003e\n\u003cp\u003eIn cervids, mesothelioma was diagnosed in a \u003cem\u003eCervus alfredi\u003c/em\u003e in Germany, kept under human care, reinforcing the hypothesis of a predisposition in captive animals (Bazin et al., 2022). The tumor has also been reported in a free-living wild pig in Italy, with peritoneal involvement, reinforcing its infiltrative and disseminative nature (Colombino et al. 2019). In addition, a recent case documented pleural mesothelioma in a \u003cem\u003eZalophus californianus\u003c/em\u003e kept under human care in an aquarium in Japan, showing that the tumor can also affect marine mammals (Takami et al. 2023). In all these reports, the disease presented a chronic character, with nonspecific clinical signs such as cachexia, cavitary effusions and lethargy, and was often diagnosed only at necropsy, bringing points in common to the picture presented by the individual with \u003cem\u003eCerdocyon thous\u003c/em\u003e in the present report.\u003c/p\u003e\n\u003cp\u003eRegarding mesothelioma in wild canids, significant similarities can be seen between the present report and the case reported by Stewart (1966) in an \u003cem\u003eLycaon pictus\u003c/em\u003e kept in a zoo in Philadelphia, United States. In both cases, the tumor presented an infiltrative and disseminative character, extensively affecting the serous of the body cavities. In \u003cem\u003eLycaon pictus\u003c/em\u003e, the neoplasm was identified in the pleura, resulting in multiple irregular masses associated with thoracic effusion, a pattern similar to that observed in the present report, in which the neoplasm diffusely affected the omentum, forming firm and white-haired masses. In addition, in both cases, histopathology revealed neoplastic cells organized predominantly in a solid pattern, with eosinophilic cytoplasm and vacuolated nucleus, in addition to occasional mitosis, reflecting aggressive behavior. Another point in common is that both individuals were kept under human care, raising the hypothesis that environmental factors and exposure to possible carcinogenic agents may be involved in the pathogenesis of the disease.\u003c/p\u003e\n\u003cp\u003eThis is the first report of epithelioid mesothelioma affecting the omentum in an individual of \u003cem\u003eCerdocyon thous\u003c/em\u003e, contributing to the knowledge and description of a malignant neoplasm in a wild canid of the Brazilian fauna. These findings reinforce the need for additional studies on the occurrence of mesotheliomas in wild animals and their possible correlation with the captive environment, since environmental factors may play a role in carcinogenesis and should be considered in the sanitary and epidemiological surveillance of these animals.\u003c/p\u003e"},{"header":"Declarations","content":"The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. The authors have no relevant financial or non-financial interests to disclose. All authors contributed to the conception and design of the study. The initial care of the patient was performed by Sandra Helena Ramiro Corrêa, the exams were performed by João Paulo da Silva Cavasani and Caroline Argenta Pescador, the data collection was performed by Osvaldo Lírio Corrêa and Thais Oliveira Morgado. The first version of the manuscript was written by Osvaldo Lírio Corrêa and all authors commented on the previous versions of the manuscript. All authors have read and approved the final manuscript.\u003cp\u003e\u003cstrong\u003eEthics approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was developed with data from the medical records of an animal treated in the hospital routine of the Wild Animals Sector of the Federal University of Mato Grosso (UFMT) and from the report of the Veterinary Pathology Laboratory of UFMT. The animal died spontaneously and therefore did not have a registration number in Ethics Committee - Use of Animals (CEUA) - UFMT.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBazin M, Schwinn J, K\u0026uuml;hl B, Armando F, Beineke A (2022). Malignant epithelioid mesothelioma in a Visayan spotted deer (\u003cem\u003eCervus alfredi\u003c/em\u003e). Berl und M\u0026uuml;nch Tier\u0026auml;rztl Wochenschr, 135. http://dx.doi.org/10.2376/1439-0299-2021-28\u003c/li\u003e\n\u003cli\u003eBollo E, Scaglione FE, Tursi M, Schr\u0026ouml;der C, Degiorgi G, Belluso E, Capella S, Bellis D (2011) Malignant pleural mesothelioma in a female Lion (\u003cem\u003ePanthera leo\u003c/em\u003e). Res Vet Sci. 91:116\u0026ndash;8. https://doi.org/10.1016/j.rvsc.2010.08.005\u003c/li\u003e\n\u003cli\u003eBrown CC, Baker DC, Barker IK (2007) Alimentary system. In: Jubb K, Palmer\u0026rsquo;s (ed) Pathology of domestic animals, 5 ed. Elsevier, New York, pp. 294\u0026ndash;296\u003c/li\u003e\n\u003cli\u003eBueno AD, Motta JC (2004). Food habits of two syntopic canids, the maned wolf (\u003cem\u003eChrysocyon brachyurus\u003c/em\u003e) and the crab-eating fox (\u003cem\u003eCerdocyon thous\u003c/em\u003e), in southeastern Brazil. Rev Chil de Historia Nat, 77: 5-14.\u003c/li\u003e\n\u003cli\u003eColombino E, Capella S, Casalinuovo F, Racco R, Pruiti F, Volante M, Lo Presti VDM, Belluso E, Capucchio MT (2019). Malignant peritoneal mesothelioma in a boar who lived in Calabria (Italy): Wild animal as sentinel system of human health. Sci of the Total Environ, 683: 267-274. https://doi.org/10.1016/j.scitotenv.2019.05.254\u003c/li\u003e\n\u003cli\u003eD'Aquino I, Piegari G, Casciaro SM, Prisco F, Rosato G, Silvestre P, Uberti BD, Capasso M, Laricchiuta P, Paciello O, Russo V (2022). An overview of neoplasia in captive wild felids in southern Italy zoos. Front in Vet Sci, 9. https://doi.org/10.3389/fvets.2022.899481\u003c/li\u003e\n\u003cli\u003eFrank AL, Joshi TK (2014) The global spread of asbestos. Annals of global health, 80(4): 257-262. https://doi.org/10.1016/j.aogh.2014.09.016\u003c/li\u003e\n\u003cli\u003eIUCN (2024) The IUCN Red List of Threatened species. International Union for Conservation of Nature\u0026rsquo;s. https://www.iucnredlist.org/species/4248/81266293. Acesso em 15 de outubro de 2024.\u003c/li\u003e\n\u003cli\u003eJuarez KM, Marinho-Filho J (2002). Diet, habitat use, and home ranges of sympatric canids in Central Brazil. J of Mammal, 83: 925-933. https://doi.org/10.1644/1545-1542(2002)083\u0026lt;0925:DHUAHR\u0026gt;2.0.CO;2\u003c/li\u003e\n\u003cli\u003eJunginger J, Hansmann F, Herder V, Lehmbecker A, Peters M, Beyerbach M, Wohlsein P, Baumg\u0026auml;rtner W (2015). Pathology in captive wild felids at German zoological gardens. PLoS One, 10(6). https://doi.org/10.1371/journal.pone.0130573\u003c/li\u003e\n\u003cli\u003eKim SM, Oh Y, Oh SH, Han JH (2016). Primary diffuse malignant peritoneal mesothelioma in a striped skunk (\u003cem\u003eMephitis mephitis\u003c/em\u003e). J of Vet Med Sci, 78(3): 485-487. https://doi.org/10.1292/jvms.15-0377\u003c/li\u003e\n\u003cli\u003eMcAloose D, Newton AL (2009) Wildlife cancer: a conservation perspective. Nat rev cancer, 9(7): 517-526. https://doi.org/10.1038/nrc2665\u003c/li\u003e\n\u003cli\u003eRocha PRD, Duarte RP, Laranjeira MG, Melo TAL, Azevedo EZ, Garcia SD, Machado GF (2019) Hemot\u0026oacute;rax fatal causado por mesotelioma pleural em um le\u0026atilde;o. Pesqui Vet Bras, 39, 416-418. https://10.1590/1678-5150-PVB-6184.\u003c/li\u003e\n\u003cli\u003eShin NS, Kwon SW, Kim DY, Kweon OK, Seo IB, Kim JH (1998). Metastatic malignant mesothelioma in a tiger (\u003cem\u003ePanthera tigris\u003c/em\u003e). J of Zoo and Wildl Med, 81-83.\u003c/li\u003e\n\u003cli\u003eSouza FDAL, de Carvalho CJS, de Almeida HM, Pires LV, dos Santos Silva L, Costa FAL, de Sousa Silva SMM (2013). Peritoneal mesothelioma in a jaguar (\u003cem\u003ePanthera onca\u003c/em\u003e). J of Zoo and Wildl Med, 44(3): 737-739. https://doi.org/10.1638/2010-0122R5.1\u003c/li\u003e\n\u003cli\u003eStewart HL (1966). Pulmonary cancer and adenomatosis in captive wild mammals and birds from the Philadelphia Zoo. J of the Natl Cancer Inst, 36(1): 117-138.\u003c/li\u003e\n\u003cli\u003eTakami Y, Tanaka M, Morita M, Maruno T, Anai N, Sudo T, Kezuka C, Izawa T, Yamate J, Kuwamura M. (2023). Pleural mesothelioma in a California sea lion (\u003cem\u003eZalophus californianus\u003c/em\u003e). J of Vet Med Sci, 85(9), 1030-1033. https://doi.org/10.1292/jvms.22-0457\u003c/li\u003e\n\u003cli\u003eTeixeira RH, Caiaffa MG, Silva ML, Silveira JP, Nemer VC, Costa ALMD (2022). Mesotelioma peritoneal em on\u0026ccedil;a-pintada (\u003cem\u003ePanthera onca\u003c/em\u003e Linnaeus, 1758). Cl\u0026iacute;n Vet, 27(158), 22-32.\u003c/li\u003e\n\u003cli\u003eTroncoso I, Brown J, Isla C, Lajara JM, Ebner M, Fehrmann-Cartes K (2024). Case report: Abdominal mesothelioma in \u003cem\u003eAtelerix albiventris\u003c/em\u003e. Front in Vet Sci, 11: 1341815. https://doi.org/10.3389/fvets.2024.1341815\u003c/li\u003e\n\u003cli\u003eTsao AS, Wistuba I, Roth JA, Kindler HL (2009) Malignant pleural mesothelioma. J of Clin Oncol, 27(12): 2081-2090. https://doi.org/10.1200/JCO.2008.19.8523\u003c/li\u003e\n\u003cli\u003eWiedner EB, Isaza R, Lindsay WA, Case AL, Decker J, Roberts J (2008). Pericardial mesothelioma in a Bengal tiger (\u003cem\u003ePanthera tigris\u003c/em\u003e). J of Zoo and Wildl Med, 39(1): 121-123. https://doi.org/10.1638/2007-0080.1\u003c/li\u003e\n\u003cli\u003eWilson DW, Dungworth DL (2002) Tumors of the respiratory tract. In: Meuten D J (ed) Tumors in Domestic Animals, 4 ed. Iowa State Press, Ames, pp 398-399\u003c/li\u003e\n\u003cli\u003eWhiton A, Schumacher J, Evans EE, Novak JM, Crews A, Ramsay E, Donnell R (2013). Mesothelioma in two nondomestic felids: North American cougar (\u003cem\u003eFelis concolor\u003c/em\u003e) and cheetah (\u003cem\u003eAcinonyx jubatus\u003c/em\u003e). Case Rep in Vet Med, 1: 286793. https://doi.org/10.1155/2013/286793\u003c/li\u003e\n\u003cli\u003eZachary JF (2018) Bases da Patologia em Veterin\u0026aacute;ria. Elsevier, Rio de janeiro.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Neoplasm, captivity, canids, wild animals, histopathological","lastPublishedDoi":"10.21203/rs.3.rs-6455256/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6455256/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Mesothelioma is a malignant neoplasm considered rare, which has a mesothelial origin, affecting the cells that line body cavities and can affect humans, domestic animals and wild animals. In wild canids, it proves to be a rare find. The objective of the present study is to describe the macroscopic, histopathological and immunohistochemical aspects of a case of epithelioid mesothelioma in Cerdocyon thous, female, aged approximately 14 years and resident at the Center for Medicine and Research in Wild Animals of the Federal University of Mato Grosso. The individual presented with a severe clinical condition and rapid progression of signs. Despite the immediate start of supportive treatment, the animal died on the same day, being sent for necropsy. Macroscopically, multiple irregular, firm, reddish-white masses were observed in the omentum. In the histopathological analysis, it consisted of proliferation of neoplastic cells with a solid pattern, where the cells were predominantly rounded, with a slightly eosinophilic and normally broad cytoplasm, with a rounded, broad, normally vacuolated, basophilic and sometimes multiple nucleus. Anisocytosis and anisocariosis with mild to moderate intensity and mild cellular pleomorphism were also present. In addition, two to eight mitosis figures were observed in the field of higher magnification. The neoplastic population was supported by a delicate stroma of connective tissue that was sometimes thick and formed delicate septa. With this, the occurrence and first report of epithelioid mesothelioma in Cerdocyon thous is confirmed, contributing to the knowledge and description of a malignant neoplasm in a wild canid.","manuscriptTitle":"Epithelioid mesothelioma in a Crab-eating Fox - Cerdocyon thous (Linnaeus, 1766)","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-03 07:45:23","doi":"10.21203/rs.3.rs-6455256/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"f772c28a-f15b-4b68-828f-c0e83d16d1c0","owner":[],"postedDate":"June 3rd, 2025","published":true,"recentEditorialEvents":[{"type":"decision","content":"Withdrawn","date":"2026-05-18T09:46:41+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-05-18T09:55:30+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-03 07:45:23","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6455256","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6455256","identity":"rs-6455256","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}