DISEASE SUMMARY PAGE

Neoplasia in Bears

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Summary Information
Diseases / List of Miscellaneous / Metabolic / Multifactorial Diseases / Disease summary
Alternative Names Tumours in Bears
Disease Agents --
Infectious Agent(s) --
Non-infectious Agent(s) --
Physical Agent(s)
General Description Hepatic and bile duct neoplasia is common in bears. See: Hepatic and Bile Duct Neoplasia in Bears
  • Neoplasms recorded at the San Antonio Zoo in bears included skin fibroma, adrenal gland adenocarcinoma and kidney adenoma in Ursus arctos - Brown bear, and kidney adenoma, skin fibroma and small intestinal leiomyoma in Ursus maritimus - Polar bear (over a ten year period). [1983](J2.14.w1)
  • In a survey of zoo-kept Tremarctos ornatus - Spectacled bears, mass lesions reported in the thorax included "mesothelioma, thymoma, cardiac rhabdomyosarcoma, poorly differentiated carcinoma involving the lung and heart and an unspecified anterior mediastinal mass." (P77.1.w19)
  • In an adult female Ursus americanus - American black bear, a follicular cystadenoma was present in the right lobe of the thyroid, and a pheochromocytoma was found in the medulla of the right adrenal gland. (J2.35.w1)
  • Lymphoblastic lymphosarcoma was diagnosed in a seven-year-old male brown bear (Ursus arctos - Brown bear). The bear had a seven month history of clinical signs including depression, anorexia and watery diarrhoea, unresponsive to symptomatic treatment including fluid therapy. At necropsy, the bear was in poor physical condition. Numerous firm tan nodule, 1-1.5 cm diameter were present throughout the liver, neoplastic nodules were found in the small intestine, causing severe thickening and corrugation of the mucosal surface, mesenteric lymph nodes were enlarged (6 x 8 cm diameter), bulging and firm, tan on the cut surface. Histologically, the neoplastic masses were found to consist of a dense population of neoplastic lymphoid cells, with round hyperchromatic nuclei, a small amount of cytoplasm and few mitotic figures. The diagnosis was lymphoblastic lymphosarcoma. (J415.2.w1)
  • An anaplastic tumour was detected in a 17-year-old grizzly bear (Ursus arctos - Brown bear) at Calgary Zoo. There were numerous masses, 1-30 cm diameter, yellow-white in colour, firm with cystic spaces, or haemorrhagic, friable and necrotic, invading the liver, spleen and abdominal lymph nodes, with a thick layer of cells over the serosal surfaces in the abdomen. Flow cytometry indicated many tetraploid cells. Histopathology indicated that the tumour probably was not hepatocellular, but did not give a definite tissue of origin. (P1.1991.w8)
  • Among mammals at the Philadelphia Zoological Gardens, mammary neoplasias were found in an 18-year-old grizzly bear (Ursus americanus - American black bear) and a 25-year-old Ursus arctos - Brown bear. A carcinoma of the tongue was seen in a male Ursus americanus - American black bear and a malignant melanoma was found on the tongue of a female Japanese brown bear (Ursus arctos - Brown bear). Once case each of thyroid gland carcinoma, pancreatic carcinoma and adrenal carcinoma were seen in three bears (species not specified). (J421.19.w1)
  • In a 30-year-old Melursus ursinus - Sloth bear at Amsterdam Zoo, a mesothelioma was found. There were about 25 litres of yellowish fluid in the abdominal cavity. (J423.69.w1)

Head

  • A laryngeal squamous cell carcinoma was found in a captive ten-year-old female Ursus americanus - American black bear. Clinically, the bear had developed occasional coughing and intermittent stertorous breathing. On anaesthesia, a mass was found to obstruct the glottis. This was 8 x 6 x 5 cm, multilobular, semifirm, tan to red-black in colour and asymmetric. It infiltrated the larynx and epiglottis and extended to the tonsils on both sides. There was a smaller lingual mass on the dorsal tongue. Histologically, the mass was composed of nests of keratinised squamous epithelial cells. Neoplastic cells were found also in regional lymphatics and lymph nodes, indicating lymphatic spread and metastasis to the lymph nodes. (J2.36.w1). 
  • A mandibular squamous cell carcinoma was diagnosed in a captive, wild-caught adult (about six years old) female Helarctos malayanus - Sun bear. Initially a red, swollen mass, 2 cm diameter was noted on the gingiva, along the lingual surface of the incisors in the mandible. The mass grew and was associated with ptylism. Biopsy gave a strong indication of adenocarcinoma. The bear was treated by bilateral rostral mandibulectomy, with cisplatin gel injected at the margins of the incision site before the wound was closed. After surgery, radiation therapy was given (there was histological indication of incomplete tumour excision) and one additional cisplatin treatment was administered. No recurrence had occurred after two years. Histopathological examination of the excised tissue confirmed squamous cell carcinoma. (J2.36.w2)
  • An oral squamous cell carcinoma with secondary osteomyelitis of the mandible was reported in an adult Tremarctos ornatus - Spectacled bear. (P77.1.w19)
  • An osteoblastoma-like osteosarcoma was diagnosed in an 11-month-old male captive-born Ursus arctos - Brown bear. Clinically, the growth developed as a nodular protuberance, 3 cm diameter, on the right maxilla, adjacent to the second to fourth incisors, with recurrence after excision. The tumour was classified (WHO classification) as an osteosarcoma, with excessive mitosis in the cellular zone of the tumour suggesting malignancy, while the intermediate and bony zones histologically appeared more as a benign osteoblastoma. (J26.25.w2)
  • Among mammals at the Philadelphia Zoological Gardens, a carcinoma of the tongue was seen in a male Ursus americanus - American black bear and a malignant melanoma was found on the tongue of a female Japanese brown bear (Ursus arctos - Brown bear). (J421.19.w1)
  • In rescued "dancing bears" Melursus ursinus - Sloth bear, in India, oral masses were found in several bears. Histopathology of one mass revealed a cementifying fibroma. (J60.12.w1)
  • A cementoma (benign fibro-cemento-osseous lesion around the apex of teeth) was found in a rescued wild-caught "dancing" Melursus ursinus - Sloth bear. (P106.2007.w20)

Gastrointestinal

  • Neoplasms reported at the National Zoological Park, Washington, 1975-1977 included a gastric leiomyoma and lipoma in an Ursus americanus - American black bear. (B39.w4)
  • A survey of 512 bears from 50 zoos in the USA, Canada and Mexico reported several cases of gastrointestinal neoplasia: pancreatic adenocarcinoma in a Melursus ursinus - Sloth bear, pancreatic adenoma in an Ursus thibetanus - Asiatic black bear, squamous cell carcinoma in a Tremarctos ornatus - Spectacled bear and an Ursus americanus - American black bear, malignant melanoma of the hard palate in an Ursus arctos - Brown bear, an unspecified small intestinal neoplasia in a Helarctos malayanus - Sun bear, intestinal adenocarcinoma in a Helarctos malayanus - Sun bear and an Ursus arctos - Brown bear, disseminated abdominal adenocarcinoma in an Ursus arctos - Brown bear, intestinal lymphosarcoma in an Ursus arctos - Brown bear (possibly causing mesenteric torsion), lymphosarcoma (affecting hepatic and renal tissues) in an Ursus thibetanus - Asiatic black bear, lymphocytic lymphoma in an Ursus arctos - Brown bear and papillary cystadenocarcinoma in a Helarctos malayanus - Sun bear. (P1.2002.w5)
  • A squamous cell carcinoma was diagnosed in a 25-year-old female Helarctos malayanus - Sun bear. The bear had developed a swelling along the left mandible and examination under anaesthesia revealed an ulcerating tumour. (P85.1.w4)
  • A pyloric leiomyoma was found in a Helarctos malayanus - Sun bear with post-prandial vomiting; contrast radiography of the stomach showed an extraluminal pyloric mass. At laparotomy, the 3 cm diameter intramural mass was removed by longitudinal incision of the pylorus. Grossly, the mass was firm and yellow-white, with a cauliflower-like appearance on cross section. Histologically the diagnosis was of a leiomyoma. (P1.1983.w1)
  • An argentaffin carcinoma (carcinoid) was diagnosed histologically in a nine-year-old female Syrian brown bear (Ursus arctos - Brown bear) with progressive depression, loss of appetite and reduced production of faeces. In the abdomen there were several litres of serosanguinous fluid and two large masses associated with the pyloric area and the proximal jejunum. multiple organs were involved and the bear was euthanased. Histologically the tumours consisted of sheets of uniform cells with eosinophilic cytoplasm and large hyperchromic nuclei. (P1.1986.w1)
  • Intestinal lymphosarsocoma was diagnosed in a grizzly bear (Ursus arctos - Brown bear). The bear was lethargic and anorectic, and stranguria occurred; later the abdomen became distended with murky red-brown fluid ( 6 L removed by abdominocentesis) and the bear became dyspnoeic. A friable, egg-shaped mass 12 x 18 cm was found at the distal end of the ileum; there were necrotic and suppurative areas in the mass and the wall of the ileum was necrotic and perforated. The mass consisted histologically of "a diffuse population of lymphoid cells with a round to oval, indented nucleus, clumped chromatin, one or more prominent nucleoli, and a scant rim of basophilic cytoplasm." There was infiltration of the ileal wall by the neoplastic cells, and they were present in the spleen and kidneys. (J4.185.w5)
  • A pancreatic carcinoma was diagnosed in an adult female Ursus arctos - Brown bear. Regurgitation, including of coagulated blood, anorexia, production of black, greasy faeces, and ataxia were noted. Physical examination under anaesthesia revealed jaundice and an intra-abdominal effusion. The bear had a leucocytosis, hypoproteinaemia, hyperbilirubinaemia and increased liver and kidney enzymes. On the duodenal wall was a firm, lobulated, circumscribed nodule which arose from the pancreas and was diagnosed as a pancreatic carcinoma. This had obstructed the bile duct; the liver was firm and swollen with a yellowish marbled pattern on its cut surface and there was massive dilatation of the gall bladder, ducti cysticus, hepaticus and choledochus, with a thickened wall and containing about 2 litres of bile. (P6.4.w5)
  • Neoplasms recorded at the San Antonio Zoo in bears included small intestinal leiomyoma in Ursus maritimus - Polar bear. [1983](J2.14.w1)
  • In a Tremarctos ornatus - Spectacled bear, which had clinical signs of general debility, anorexia, lethargy, anaemia and elevated blood urea, two neoplasms were found; one was pyloric distension due to a leiomyoma. (J51.35.w1)

Ocular

  • A survey of 512 bears from 50 zoos in the USA, Canada and Mexico reported one Helarctos malayanus - Sun bear with "squamous cell carcinoma of the left eye, keratitis of the right eye, and melanoma of the eyelid"). (P1.2002.w5)
  • Myxoma of the palpebral conjunctiva has been reported in a captive bear. (B16.9.w9)

Pancreatic

  • Pancreatic beta-cell carcinoma has been reported in Ursus maritimus - Polar bear. (B336.51.w51)
  • At Taronga Zoo, pancreatic adenoma with extensive fibrosis was seen in a 35-year-old or older male Ursus arctos - Brown bear. Clinically, the bear had an 18-month history of periodic vomiting and regurgitation, lethargy and anorexia. The tumour was a firm spherical mass, about 9 cm diameter, involving the pancreas and a dilated pancreatic duct. The cut surface showed firm white tissue surrounding ovoids of yellow-brown bulging tissue, some haemorrhagic in the centre. Histologically, the mass was found to consist of lobules of large pancreatic acinar cells with some anisokaryosis. There were no islets; thick bands of mature connective tissue surrounded the lobules. (J2.21.w2)
  • A survey of 512 bears from 50 zoos in the USA, Canada and Mexico reported pancreatic adenocarcinoma in a Melursus ursinus - Sloth bear and pancreatic adenoma in an Ursus thibetanus - Asiatic black bear. (P1.2002.w5)
  • Among mammals at the Philadelphia Zoological Gardens, one case of pancreatic carcinoma was seen (species not specified). (J421.19.w1)
  • A pancreatic carcinoma of acinar origin (pancreatic parenchymal cell carcinoma) with multiple hepatic metastases was found in an adult (31 year old) Kodiak bear (Ursus arctos - Brown bear). Clinical signs include loss of appetite, weight loss, eventually emaciation and weakness. In the head of the pancreas there was a large, elliptical, stony hard growth, 8 x 6 x 3 cm, salmon coloured on cross section with bands of white fibrous tissue; there were many soft cystic areas containing semi-liquified tissue. The liver was grossly enlarged, over 5.5 kg, with many round pink-white metastatic nodules, visible on the liver surface and replacing much of the liver parenchyma. Many of the liver nodules contained necrotic or haemorrhagic areas. The retroperitoneal lymph nodes were enlarged, firm and contained grey-white areas. Histopathologically, there were two cellular patterns. In one, cells were arranged in pseudo-acinar groupings or thick tortuous cords with papillary projections. The cells had abundant cytoplasm containing many eosinophilic zymogen granules, and large vesicular hyperchromatic nuclei with prominent deep-staining nucleoli; there were infrequent mitotic figures. The second predominant pattern was epithelioid cords of small cells with dark pyknotic nuclei and scant cytoplasm filled with vacuoles which stained with Sudan III for neutral fat; zymogen granules were present in some cells. The stroma was loose highly vascular connective tissue. Close to the tumour the pancreas showed parenchymal atrophy and dense interstitial fibrosis. (J352.14.w1)
  • Multiple pancreatic islet cell adenomas and carcinomas were found in a 25-year-old wild-born Ursus maritimus - Polar bear at Lincoln Park Zoo, Chicago. At necropsy the bear's pancreas weighed 600 g and contained multiple 2-8 mm diameter, firm, cream coloured nodules. Histopathology showed a uniform population of neoplastic cells in the nodules, some well encapsulated by dense connective tissue not containing any neoplastic cells and therefore diagnosed as adenomas, while the connective tissue around other nodules was invaded by neoplastic cells, with these nodules therefore diagnosed as carcinomas. The neoplastic cells were large, polyhedral, with finely granulated eosinophilic cytoplasm, large, spherical hyperchromatic nuclei and cytoplasmic granules with staining indicating their beta cell origin. Clinical signs prior to death included lack of wound healing, development of abscesses, reduced activity, reduced appetite and weight loss. (J26.17.w2)

Renal:

  • Neoplasms recorded at the San Antonio Zoo in bears included kidney adenoma in Ursus arctos - Brown bear, and in Ursus maritimus - Polar bear (over a ten year period). [1983](J2.14.w1)
  • In a 36-year-old Ursus maritimus - Polar bear, an incidental necropsy finding was a unipolar renal tubular adenoma in one kidney, 3 cm diameter, well demarcated from the surrounding tissue and histologically benign. (J2.33.w1)
  • In a 22-year-old male Ursus maritimus - Polar bear with hepatocellular carcinoma at Basle Zoo, a 2 cm diameter firm white nodule in the right kidney was found on histopathology to be a small adenoma. (P6.2.w7)

Reproductive (including mammary)

Thymus

  • In a polar bear (Ursus maritimus - Polar bear), hind limb weakness progressed over a day, with sternal recumbency and forelimb weakness the following day; the condition did not improve with supportive treatment. A spindle cell thymoma (described from histopathological examination) was found at necropsy, para-aortic, 6.0 x 4.0 x 6.0 cm, in the cranial mediastinum, consisting of friable, apparently necrotic material. Additionally there was a degenerative intervertebral disc at L7/S1 and oedema of the spinal cord in this area. Serum from the bear had an acetylcholine receptor antibody titre of 0.86 nmol/L, which would be compatible with myasthenia gravis in cats and dogs. (P504.2001.w3, J2.35.w2) See: Myasthenia Gravis in Bears
  • In a Tremarctos ornatus - Spectacled bear, which had clinical signs of general debility, anorexia, lethargy, anaemia and elevated blood urea, two neoplasms were found. An extensive mass anterior to the heart measured about 150 x 100 mm, with a surface smooth in some areas but cauliflower-like in others, and lobulated on cross section. Histologically plump cells with oval vesicular nuclei were arranged in whorls and bundles, with cystic areas and areas of calcification; based on the cellular morphology, this was identified as a spindle cell thymoma. There was also pyloric distension due to a leiomyoma. (J51.35.w1)
Further Information --
Associated Techniques
Host taxa groups /species Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" module has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

List does not contain all other species groups affected by this disease. [N.B. Miscellaneous / Traumatic Diseases tend to be under-reported and the majority are likely to affect all bird and mammal species, given exposure to the related disease agents/factors.]

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