Epidemiology of neoplasia in captive black-footed ferrets (Mustela nigripes), 1986-1996.

The epidemiology of neoplastic disease was studied retrospectively in the captive population of black-footed ferrets (Mustela nigripes). Postmortem reports were reviewed and archived tissues examined from 184 of the 227 adult (>1 yr old) black-footed ferrets that died from the beginning of the current captive propagation program in late 1985 to the end of 1996. A total of 185 neoplasms, of 28 distinct phenotypes, were seen in 102 (55.4%) of these ferrets. There was more than one tumor type present in 51 ferrets. Tumors of the apocrine glands (28.3%), renal tubular neoplasms (20.7%), and biliary cystadenoma or carcinoma (20.1%) were the most common neoplasms. The probability of developing most types of neoplasms increased with age. Neoplasms of the apocrine glands were more common in males and may be hormonally influenced. The unusually high prevalence of biliary cystadenocarcinoma may be secondary to the common occurrence of intrahepatic biliary cysts in this population. Although neoplasia is an important cause of mortality in captive adult black-footed ferrets, its impact on captive propagation of the species, and on the wild population, is probably limited because clinically significant tumors are encountered almost exclusively in postreproductive ferrets (>3 yr old) and because ferrets released into their natural habitat rarely reach susceptible age.     

Mortality of captive black-footed ferrets (Mustela nigripes) at Smithsonian's National Zoological Park, 1989-2004.

Black-footed ferret (Mustela nigripes) mortality was investigated retrospectively based on the pathology records of 107 captive animals held at Smithsonian's National Zoological Park from 1989 to 2004. The majority of deaths in neonates were due to cannibalism (n = 42; 64.6%) and maternal trauma (n = 11; 16.9%); both of these causes of mortality decreased during the study period. Prior to 2001, juvenile mortality was most often caused by gastrointestinal disease (n = 11; 52.4%), including coccidiosis, salmonellosis, and clostridium infection. In 2001, improvements in husbandry, hygiene, and medical treatment led to decreases in juvenile mortality associated with gastrointestinal disease. The most common causes of death in adult ferrets were renal or neoplastic disease. The etiology of the high prevalence of renal disease in the last 4 yr of the study is unknown; it was not associated with increasing age or inbreeding. Improved hygiene and vigilant monitoring for signs of gastrointestinal and renal disease will continue to improve the success of the captive propagation of this species.     

Renal neoplasia in coypus (Myocastor coypus).

Renal neoplasia is described in coypus (Myocastor coypus) from a feral population of the species in East Anglia. A population control campaign was started in 1962, and in 1981 this became an eradication scheme. From 1976 onwards, a research programme included the postmortem examination of 9400 wild caught and captive coypus. During the period 1980-91, 15 cases (0.16%) of renal neoplasia were detected. The tumours were found in both sexes between estimated ages of 25 months and 13 years with no significant sex prevalence. There was no clear evidence that renal tumours were more common in older animals. Tumours were most common in captive coypus and were bilateral in approximately half of the animals. In all cases, the tumours were of epithelial type resembling adenomata and adenocarcinomata of other animals. Most were clearly benign, and, although some showed evidence of malignancy, no unequivocal evidence of metastasis was established. The prevalence of renal tumours in this series is greater than that recorded in previous published surveys of coypus and other rodents. This may relate to the origin of the coypus population, differences in age structure in animals examined, and the varied conditions under which the rodents lived. Aetiological factors remain undetermined.     

Amyloidosis in the black-footed ferret (Mustela nigripes).

This study describes clinical, histologic, immunohistochemical and electron microscopic features of amyloid A amyloidosis occurring in black-footed ferrets (Mustela nigripes) from eight U.S. zoological institutions. Ferrets had nonregenerative anemia, serum chemistries consistent with chronic renal disease, and proteinuria. Amyloid was present in a variety of tissues, but it was most severe in renal glomeruli and associated with tubular protein loss and emaciation. Congo red/potassium permanganate (KMnO4) and immunohistochemical stains revealed that the amyloid was of the AA type. Concurrent diseases and genetic predisposition were considered the most important contributing factors to development of amyloidosis. Analysis of the genetic tree did not reveal convincing evidence of a common ancestor in the affected ferrets, but a genetic predisposition is likely because all the captive black-footed ferrets are related.     

A retrospective study (2006-2020) of cytology and biopsy findings in pet rabbits (Oryctolagus cuniculus), ferrets (Mustela putorius furo) and four-toed hedgehogs (Atelerix albiventris) seen at an exotic animal clinic in Tokyo,Japan

Background: Rabbits, ferrets, and four-toed hedgehogs are popular exotic pets, but comprehensive epidemiological studies in these animals have been rarely conducted. The present study aims to clarify the incidence of neoplastic and non-neoplastic diseases in pet rabbits, ferrets and four-toed hedgehogs in Japan. Methods: We histologically/cytologically investigated 1098 samples from 883 rabbits, 812 samples from 521 ferrets and 561 samples from 468 four-toed hedgehogs that were collected at Miwa Exotic Animal Hospital and submitted to the Laboratory of Veterinary Pathology, The University of Tokyo between 2006 and 2020. The examinations of necropsy samples were not included in the present study. Results: Of the 1098 samples from diseased rabbits, 721 (65.7%) were diagnosed as neoplastic and 377 (34.3%) were as non-neoplastic. Uterine adenocarcinoma (21.1%), cutaneous soft tissue sarcoma (15.1%) and mammary gland adenocarcinoma (8.2%) were the most commonly encountered neoplasms. Endometrial hyperplasia (35.8%), testicular atrophy (4.2%) and uterine adenomyosis (3.7%) were the most common non-neoplastic lesions in rabbits. Of the 812 samples from diseased ferrets, 487 (60.0%) were diagnosed as neoplastic and 325 (40.0%) were as non-neoplastic. Adrenocortical tumor (23.2%), lymphoma (19.3%) and pancreatic islet cell tumor (11.5%) were the most commonly encountered neoplasms. Extramedullary hematopoiesis in the spleen (10.5%), lymph node hyperplasia (7.7%) and cholangiohepatitis (4.6%) were the most common non-neoplastic lesions in ferrets. Of the 561 samples from diseased hedgehogs, 338 (60.2%) were diagnosed as neoplastic and 223 (39.8%) were as non-neoplastic. Endometrial stromal tumor and endometrial mixed tumor (23.7%), oral squamous cell carcinoma (13.0%) and cutaneous soft tissue sarcoma (11.5%) were the most commonly encountered neoplasms. Gingivitis/stomatitis (39.5%), endometrial hyperplasia (18.8%) and dermatitis (6.7%) were the most common non-neoplastic lesions in hedgehogs. Conclusions and clinical relevance: Information obtained from the present study will provide a useful reference for veterinarians working with these exotic animals. Based on the literature search, this is the largest-scale retrospective study on disease incidence in hedgehogs.     

Necropsy and histopathologic findings in 14 African hedgehogs (Atelerix albiventris): a retrospective study.

From fiscal years 1992 through 1996, 14 African hedgehog (Atelerix albiventris) cases were submitted to the Animal Disease Diagnostic Laboratory at Purdue University. The most common diagnoses were splenic extramedullary hematopoiesis (91%), hepatic lipidosis (50%), renal disease (50%), and neoplastic disease (29%). Other less frequent necropsy findings were myocarditis (21%), colitis (14%), bacterial septicemia (14%), and pneumonia (14%). The data indicate that splenic extramedullary hematopoiesis, hepatic lipidosis, renal disease, and neoplasms are frequent postmortem findings in hedgehogs.     

Epidemiology of Mycobacterium bovis infection in feral ferrets (Mustela furo) in New Zealand: II. Routes of infection and excretion

Detailed necropsies of 228 ferrets captured from eight areas in the North and South Islands provided material for an investigation into the epidemiology of tuberculosis in wild ferrets. Seventy-three of the 228 (32%) animals examined were diagnosed as tuberculous, by culture of pooled lymph nodes and detailed histopathological examination. The prevalence of bovine tuberculosis was 96% in 24 ferrets taken from areas in which tuberculous possums were common. None of 35 animals under 4 months of age were found to be infected, and the prevalence of infection was shown to rise with age, such that for each 6 month age increment there was a 2.8 times greater risk of becoming infected. The most common route of infection appeared to be via the alimentary tract, as 79% of 38 animals, in which the initial lesions could be reasonably determined, had these lesions associated with the digestive tract. Samples from potential sites of excretion from infected ferrets were submitted for culturing. The most common route of excretion was via the oral cavity, with M. bovis recovered from 15 of 64 (23%) oral swabs. Mycobacterium bovis was also isolated from four of 64 (6%) tracheobronchial lavage samples, ten of 63 (16%) faecal samples, two of 29 (7%) urine samples and one of 8 (12.5%) mammary glands. The disease in ferrets appears to be principally maintained by ingestion of tuberculous carrion. Although a moderate number of ferrets excrete M. bovis orally, there appears to be only minor intraspecific transmission by bite wounding. The findings provided no evidence to support the occurrence of pseudo-vertical transmission.     

Neoplasia of captive yellow sea horses (Hippocampus kuda) and weedy sea dragons (Phyllopteryx taeniolatus)

Syngnathidae is the family of fish that includes sea horses, pipefish, and sea dragons. To date, only a single publication has described neoplasia in syngnathids, a fibrosarcoma of the brood pouch in an aquarium-reared lined sea horse (Hippocampus erectus). From 1998 until 2010, the Toronto Zoo submitted 172 syngnathids for postmortem; species included the spotted or yellow sea horse (Hippocampus kuda), the pot-bellied sea horse (Hippocampus abdominalis) and the weedy sea dragon (Phyllopteryx taeniolatus). Seven neoplasms and two neoplastic-like lesions were identified from these cases. Under light microscopy, the neoplasms had morphological characteristics of a cardiac rhabdomyosarcoma, renal adenocarcinoma, renal adenoma, renal round cell tumors, which were likely lymphomas, exocrine pancreatic carcinoma, and intestinal carcinoma. Of these neoplasms, four had clear evidence of metastasis: the pancreatic and intestinal carcinomas and both round cell tumors. As syngnathids are highly fastidious animals, they can be difficult to maintain in captivity. In order to improve their husbandry, preventative and palliative care, as well as treatment, it is important to investigate and document the types of diseases affecting syngnathids.     

Cytochrome b5 expression in gonadectomy-induced adrenocortical neoplasms of the domestic ferret (Mustela putorius furo)

Whereas the adrenal glands of healthy ferrets produce only limited amounts of androgenic steroids, adrenocortical neoplasms that arise in neutered ferrets typically secrete androgens or their derivative, estrogen. The 17,20-lyase activity of cytochrome P450 17alpha-hydroxylase/17,20-lyase (P450c17) must increase to permit androgen biosynthesis in neoplastic adrenal tissue. We screened ferret adrenocortical tumor specimens for expression of cytochrome b(5) (cyt b(5)), an allosteric regulator that selectively enhances the 17,20-lyase activity of P450c17. Cyt b(5) immunoreactivity was evident in 24 of 25 (96%) adrenocortical adenomas/carcinomas from ferrets with signs of ectopic sex steroid production. Normal adrenocortical cells lacked cyt b(5), which may account for the low production of adrenal androgens in healthy ferrets. Other markers characteristic of gonadal somatic cells, such as luteinizing hormone receptor, aromatase, and GATA4, were coexpressed with cyt b(5) in some of the tumors. We concluded that cyt b(5) is upregulated during gonadectomy-induced adrenocortical neoplasia and is a marker of androgen synthetic potential in these tumors.     

Solitary dermal leiomyosarcomas in 12 ferrets.

Twelve 3-6-year-old ferrets (8 males, 3 females, 1 unknown) were presented with single cutaneous nodules. These dermal tumors were characterized histologically by nodular proliferation of neoplastic smooth muscle fibers with marked anisokaryosis and a mitotic rate of >2 mitoses per 10 high-power fields. Neoplastic cells stained strongly for vimentin in all tumors and for smooth muscle actin and desmin in all but 1 tumor. Histologic and immunohistochemical findings suggested a diagnosis of piloleiomyosarcoma for these tumors. Excision was curative in all animals available for follow-up. However, 3 of 5 animals developed adrenal disease within 7 months after removal of the dermal leiomyosarcoma.     

Surgical Management of Adrenal Tumors and Insulinomas in Ferrets

Domestic ferrets are popular pets and comprise a significant percentage of the caseload in many veterinary practices. This article describes the diagnosis and surgical techniques for treatment of 2 common endocrine disorders affecting ferrets, adrenal gland disease and pancreatic beta cell neoplasms. Although medical treatment options are used to reduce the severity of clinical signs associated with adrenal hyperplasia or neoplasia, surgical removal of the adrenal gland(s) is the treatment of choice. Clinical disease associated with pancreatic beta cell tumors includes hypoglycemia, and in many cases the tumor will metastasize early in the course of the disease. Although achieving a complete resolution of pancreatic beta cell neoplasia is unlikely, surgical removal of insulin-secreting tumors is recommended to temporarily alleviate the clinical syndrome and confirm the diagnosis.     

Epithelioid variant of hemangioma and hemangiosarcoma in the dog, horse, and cow

Epithelioid hemangiomas, hemangioendotheliomas, and angiosarcomas are well recognized histologic variants of endothelial tumors in humans that in the past have been confused with neoplasms of epithelial or histiocytic origin. We describe 12 epithelioid endothelial vascular tumors in 8 dogs, 3 horses, and 1 cow that share microscopic features with these tumors in humans. Ten tumors were located within the dermis and subcutis, 1 in the gastrocnemius tendon, and 1 in the skeletal muscle of the thigh. Key histologic features were the plump, epithelioid appearance of neoplastic endothelial cells and occasional cytoplasmic vacuolation, which rarely contained a single erythrocyte. Patterns of epithelioid endothelial cell growth ranged from conventional vasoformative structures to glandlike acini and short ducts to solid, sheetlike arrangements. All tumors were positive for endothelial markers: 12/12 (100%) were positive for von Willebrand factor with variable intensity and distribution and 9/9 (100%) were positive for CD31. All 12 were negative for cytokeratin. We subdivided these tumors into epithelioid hemangiomas (n = 3) and hemangiosarcomas (n = 9) based on conventional morphologic criteria, growth pattern (invasive or not), and metastasis (known in 1 case at the time of biopsy). Additional follow-up information obtained by a written questionnaire was available for 6/12 (50%) animals and revealed local recurrence in 3 animals (1 epithelioid hemangioma and 2 epithelioid hemangiosarcoma) and regional metastasis in 3 animals (all epithelioid hemangiosarcomas). This series represents a novel group of vascular tumors in domestic animals of which there are only 3 previous cases reported in the veterinary literature.     

Isolation of Helicobacter mustelae from ferrets in New Zealand

AIMS: The bacterial genus Helicobacter contains over 20 species, including the human gastric pathogen H. pylori, and the mustelid-specific H. mustelae. A previous study in this country failed to isolate H. mustelae from a captive breeding colony of ferrets. We sought to confirm whether or not H. mustelae was present in this country. METHODS: A combination of bacterial culture, phenotypic testing and molecular techniques were used to isolate and identify gastric bacteria from captive and wild populations of ferrets in the New Zealand North Island. RESULTS: Bacteria were isolated from captive and wild ferrets which were phylogenetically identical to the type strain of H. mustelae. A mild to moderate gastritis was seen in five of six animals examined, and an antibody response to H. mustelae proteins was demonstrated. CONCLUSIONS: Helicobacter mustelae is not exotic to New Zealand, but is present in two populations of ferrets tested in the North Island.     

Enzootic reticuloendotheliosis in the endangered Attwater's and greater prairie chickens

Reticuloendotheliosis (RE) in captive greater prairie chickens (GPC, Tympanuchus cupido pinnatus) and Attwater's prairie chickens (APC, Tympanuchus cupido attwateri) was first reported in 1998. RE is caused by avian reticuloendotheliosis virus (REV), an oncogenic and immunosuppressive retrovirus infecting multiple species of wild and domestic birds. During August 2004 through May 2006 a captive population of prairie chickens was affected simultaneously with a neoplastic condition and also avian pox, the latter being detected in 7.4% (2 of 27) of all birds submitted for histopathology. A survey for REV was conducted in order to examine its possible role in mortality observed primarily in juvenile and adult specimens of prairie chickens. The investigative procedures included postmortem examinations, histopathology, molecular detection, and virus isolation. In total, 57 Attwater's prairie chickens and two greater prairie chickens were included in the study. REV infection was diagnosed using virus isolation or polymerase chain reaction (PCR) or both in 59.5% (28 of 47) of blood samples and/or tumors from suspect birds. Lymphosarcomas were detected in the tissues of 37% (10 of 27) of the birds submitted for histopathology. Such lymphosarcomas suggestive of RE represented the most frequent morphologic diagnosis on histopathology among 27 separate submissions of naturally dead prairie chickens. Overall, REV was detected or RE diagnosed in 34 of 59 prairie chickens (57.62%). The average death age of all birds diagnosed with lymphosarcomas on histopathology was 2.2 yr, ranging from <1 to 4 yr. Although deaths associated with neoplasia occurred in males and females in equal proportions based on submissions, overall more males were diagnosed as REV infected or RE affected (16 males vs. 7 females, and 11 birds of undetermined gender). Reticuloendotheliosis virus was confirmed as a significant cause of mortality in captive prairie chickens.     

Oviduct adenocarcinoma in some species of captive snakes

This article reports 5 cases of oviduct adenocarcinoma in adult captive snakes from Smithsonian's National Zoological Park. This neoplasm was found in 1 of each of the following species: emerald tree boa (Corallus caninus), Amazonian tree boa (Corallus enydris enydris), Burmese rock python (Python molurus bivittatus), Northern pine snake (Pituophis melanoleucus melanoleucus), and corn snake (Elaphe guttata). Grossly, tan to red firm masses were found within oviducts in 3 cases. In an additional 2 cases, the primary tumor was detected only histologically. Microscopically, neoplasms were papillary, and often extended transmurally. The neoplastic cells were polygonal and organized in acini or cords, with often abundant fibrovascular stroma. Hemorrhages and necrosis were present in all cases. Inflammation, myxomatous material, desmoplasia, and bacteria were often observed. Histologic evidence of metastasis was present in all cases. Solid metastases were seen in all animals except the Northern pine snake and involved several organs including the liver, lung, and heart. Emboli of neoplastic cells were observed in all animals but the Burmese rock python and corn snake.     

Pathology of enzootic intranasal tumor in thirty-eight goats.

Intranasal tumors were studied in 38 goats ranging from 7 months to 8 years of age of both Murciana-Granadina and crossed breeds. Tumors were diagnosed in eight herds. Clinically, the affected goats showed a copious seromucous nasal discharge, ocular protrusion, and skull deformations. The tumors originated from the ethmoid region. They involved one or both nasal cavities, although most were bilateral (26/38). The tumors were generally accompanied by inflammatory polyps. The histologic patterns were very similar in all cases, and the tumors were classified as low grade adenocarcinomas of the nasal glands. Histochemical, immunohistochemical, and ultrastructural studies suggested that the serous glands of nasal mucosa were the probable origin of the neoplastic cells. Budding and extracellular retrovirus-like particles were observed ultrastructurally in 6/8 tumors. The similarities between these caprine tumors and nasal tumors in sheep and the etiologic role of the retrovirus are discussed.     

Transitional cell carcinoma in fishing cats (Prionailurus viverrinus): pathology and expression of cyclooxygenase-1, -2, and p53

A high prevalence of urinary bladder transitional-cell carcinoma (TCC) has been noted in captive fishing cats (Prionailurus viverrinus). Of the 91 adult deaths between 1995 and 2004, 12 (13%) were attributed to TCC. To help elucidate mechanisms of carcinogenesis, archival sections of urinary bladder from 14 fishing cats were examined histologically and immunohistochemically for p53, cyclooxygenase (COX)-1, and COX-2 expression. Ten cats had TCC, and 4 were unaffected. The average age at death was 10.8 years in affected individuals and 10.5 years in unaffected individuals. There was no sex predilection. Fishing cat TCCs were characterized histologically as papillary and infiltrating (n = 6), nonpapillary and infiltrating (n = 3), or carcinoma in situ (n = 1). Glandular and squamous metaplasia, necrosis, and lymphatic invasion were prominent histologic features. Two individuals had documented metastasis. p53 nuclear immunolabeling was detected in 4/10 (40%) TCCs. In two cases, immunolabeling was limited to less than 10% of the neoplastic cellular population and was comparable to staining of normal fishing cat bladder. Therefore, p53 gene mutation did not appear to be an essential component of TCC carcinogenesis in examined fishing cats. COX-1 immunohistochemistry was negative in all cases. All TCCs had some degree of COX-2 cytoplasmic immunolabeling, which was exclusively within the invasive portions of the neoplasms. Papillary portions were uniformly negative. COX-2 overexpression was a prominent feature in the majority of the examined fishing cat TCCs, suggesting that COX-2-mediated mechanisms of carcinogenesis are important in this species and that COX-inhibiting drugs may be of therapeutic benefit.     

Epidemiology of Mycobacterium bovis infection in feral ferrets (Mustela furo) in New Zealand: I. Pathology and diagnosis

Necropsies from 228 ferrets captured from eight areas in the North and South Islands provided material for an investigation into the epidemiology of tuberculosis in feral ferrets. Mycobacterial culture of pooled lymph nodes (retropharyngeal, respiratory and jejunal) identified the prevalence of infection to be much higher than that estimated from gross lesions only. Seventy-three of the 228 animals examined (32%) were diagnosed as tuberculous. Fifty-three culture-positive ferrets and 18 seemingly uninfected animals were subjected to detailed histopathological examination. The outcomes of these investigations, including the characteristics of the disease, distribution of lesions and aids to diagnosis, are presented. Of the feral carnivores found in New Zealand, the disease persists at high prevalence only in ferrets, and is probably the maintained principally by ingestion of tuberculous carrion. The course of the disease may be prolonged in some ferrets, but tuberculosis eventually causes death of many infected animals. Microscopic hepatic granulomas may be considered pathognomonic of the disease, and have potential to be used as a rapid diagnostic tool in ferrets with no gross lesions.     

CONGENITAL ABNORMALITIES OF THE VERTEBRAL COLUMN IN FERRETS

Vertebral column pathologies requiring surgical intervention have been described in pet ferrets, however little information is available on the normal vertebral formula and congenital variants in this species. The purpose of this retrospective study was to describe vertebral formulas and prevalence of congenital vertebral anomalies in a sample of pet ferrets. Radiographs of 172 pet ferrets (96 males and 76 females) were included in this retrospective study. In 143 ferrets (83.14%), five different formulas of the vertebral column were recorded with normal morphology of vertebrae (rib attachment included) but with a variable number of thoracic (Th), lumbar (L), and sacral (S) vertebrae. The number of cervical (C) vertebrae was constant in all examined animals. Observed vertebral formulas were C7/Th14/L6/S3 (51.74%), C7/Th14/L6/S4 (22.10%), C7/Th14/L7/S3 (6.98%), C7/Th15/L6/S3 (1.74%), and C7/Th15/L6/S4 (0.58%). Formula C7/Th14/L6/S4 was significantly more common in males than in females (P < 0.05). Congenital spinal abnormalities were found in 29 ferrets (16.86%), mostly localized in the thoracolumbar and lumbosacral regions. The cervical region was affected in only one case. Transitional vertebrae represented the most common congenital abnormalities (26 ferrets) in the thoracolumbar (13 ferrets) and lumbosacral regions (10 ferrets) or simultaneously in both regions (three ferrets). Other vertebral anomalies included block (two ferrets) and wedge vertebra (one ferret). Spina bifida was not detected. Findings from the current study indicated that vertebral formulas may vary in ferrets and congenital abnormalities are common. This should be taken into consideration for surgical planning.