Neoplasia in Ferrets

Summary Information

Diseases / List of Miscellaneous / Metabolic / Multifactorial Diseases / Disease summary
Alternative Names
  • Tumours in ferrets
  • Neoplastic disease in ferrets

See also the individual pages on the major neoplastic diseases of ferrets:

Disease Agents --
Infectious Agent(s) --
Non-infectious Agent(s) --
Physical Agent(s) --
General Description Neoplasia are common in ferrets. (B602.9.w9) In the last two decades or so there have been an increasing number of reports of neoplasia in ferrets, with a wide variety of types of neoplasia, and neoplasias of all body systems, as well as multiple neoplasias within a single ferret. (B627.18.w18, B631.30.w30, J213.7.w5)
By System
  • Reported types of skin neoplasia include basal cell tumour, mastocytoma, cystic adenoma, haemangioma, fibroma, fibrosarcoma, polyp, squamous cell carcinoma, sebaceous epithelioma, mammary and preputial adenoma and adenocarcinoma, lipoma, cystadenoma, leiomyosarcoma and ceruminous gland adenocarcinoma. (J213.7.w5)
    • A review found 18% of ferret neoplasms to be tumours of the skin or subcutis; 28% of these were malignant, but mainly low-grade. (B602.9.w9)
    • Early surgical excision (to minimise the risk of metastasis) with a wide margin (to ensure infiltrative tumours are fully removed) is recommended and often curative. (B602.9.w9, J213.7.w5)
    • Note: Skin sarcomas, of whatever cellular origin, tend to have low metatatatic potential and show good prognosis following surgical excision. (B602.9.w9)
  • The most common skin tumours of 1,252 ferret neoplasias were benign and of basal cell origin (basal cell tumours); they included sebaceous epitheliomas and sebaceous adenomas. These have a warty appearance, (B602.9.w9) may be  pedunculated (B627.18.w18, J213.7.w5) or appear as raised plaques (B627.18.w18), are usually firm and white to pink, may grow quite large and due to self-trauma can look ominous (often ulcerated) , but they are usually benign. They may be irritating to the ferret and local inflammation and infection can develop secondary to self-trauma. Early surgical removal is recommended and is curative. (B602.9.w9, B627.18.w18, J213.7.w5) Occasionally the centre of the mass is necrotic and may be cavitated. (B602.9.w9)
    • More females than males have been reported to develop basal cell tumours (27 versus 12), and affected ferrets have been 1 - 12 years old, with tumours developing at all sites, particularly the head, neck, shoulder and leg (including the foot). (B627.18.w18)
    • Basal cell tumours are rarely locally invasive. Histologically, sheets, lobules or nests of well-differentiated baseloid epithelial cells are arranged in variable quantities of stroma. Cells show various degrees of squamous or sebaceous differentiation, have round to oval nuclei which are densely basophilic, and indistinct nucleoli; there is little cytoplasm, and no intracellular bridges are present. The mititic index can be very variable. (B627.18.w18)
    • Sebaceous cell tumours have been seen in ferrets of 2 - 12 years of age, and in males and females, on all sites - tail, flank, head and neck, forming firm warty verrucous masses up to 3 cm diameter and yellow, tan or brown in colour. Histologically, fibrous stroma separates multiple lobules; encapsulation is often poor. Small basophilic cells and occasional bizarre ginat cells suround sebaceous cells which are oval to cuboidal and show irregular orientation, with abundant granular and foamy to vacuolated cytoplasm. The hyperchromatic nuclei show low to high numbers of mitotic figures. Sometimes, focal ulceration, inflammation and necrosis are present. (B627.18.w18)
    • Baso-squamous-sebaceous tumours contain all three types of cells (basal, squamous and sebaceous) in varying ratios and have been described in male and female ferrets of 2 - 8 years of age (and in a polecat), from the lower jaw and groin areas. Firm, warty or pedunculated grey-white masses up to 2.2 x 1.4 x 1 cm have been described. Histologically, cribriform foci are present; solid masses of basal cells may be seen as well as squamous differentiation and keratin formation, and well-differentated sebaceous cells; the mitotic index may be low to high. (B627.18.w18) 
  • Mast cell tumours (mastocytomas) in ferrets are benign (unlike those in cats and dogs). They appear as discrete flat lesions with a yellow crust, and usually have minimal local invasion into the dermis. Surgical excision is curative but additional masses of the same type may appear on the ferret later and also need removing (the prognosis following treatment remains good). (B602.9.w9)
    • In one a study, affected ferrets were 3-6 years old (J26.30.w3)., in another study, 2-8 years old; both males and females were affected. Firm, often well-circumscribed nodules were present in the dermis; alopecia and superficial ulceration were present occasionally. The masses were variable in size and location (head, ear, neck, flank, leg, foot, tail base and prepuce). Histopathology revealed well-differentiated mast cells, round to oval, in sheets or lobules between collagen bundles. Round to oval nuclei were central in the cells and the nucleoli were occasionally prominent. The moderate cytoplasm was amphophilic; H&E stain generally produced poorly-discernable metachromatic granules but these were readily visible with toludine blue. (B627.18.w18, J26.30.w3)
  • Apocrine neoplasms (adenomas, adenocarcinomas) develop in the head, neck, prepuce and vulva  - where the scent glands are concentrated. They are generally found in the deeper layers of the skin and subcutis and are usually malignant (79% in a study) often showing aggressive local infiltration and metastasis to local lymph nodes; visceral metastases are seen occasionally. They grow rapidly and aggressively, making complete surgical excision difficult.. A wise excision margin is recommended. (B602.9.w9)
    • Found in ferrets of 1 - 10 years, mainly in the perineal area, up to 2.2 cm diameter and infiltrative. Histologically, pleomorphic cells (cuboidal to columnar) have prominent nucleoli in the vesiculated nuclei, and usually  a high mitotic index. They are found in various arrangements - tubules, cords, acini or lobules, together with intraluminal secretions, which are eosinophilic. Both perianal gland and sweat gland tumours may show focal necrosis and metastasis to local lymph nodes. (B627.18.w18)
    • Preputial adenoma/adenocarcinoma
      • If the primary neoplasm affects the prepuce, amputation of the prepuce together with perineal urethrostomy may be required. (B602.9.w9)
      • Preputial masses may be as large as 2-3 cm diameter and vary from rigid to soft or fluctuant on palpation. (B627.18.w18)
      • Histologically, the cuboidal to columnar epithelial cells may be arranged in acini, tubules or nests and vary from well-differentiated to anaplastic, with a high mitotic index. (B627.18.w18)
      • Preputial adenocarcinoma may metastasise. (B627.18.w18, J213.7.w5)
      • Radiotherapy has been used to reduce the size of a large preputial adenocarcinoma, allowing surgical excision (although cutaneous metastases occurred). (J213.7.w5)
      • A preputial adenocarcinoma which was surgically removed recurred twice despite radiotherapy. (B627.18.w18)
  • One exocrine sweat gland adenoma was seen on the foot of a ferret, in a study of 1,525 ferret neoplasias. (B602.9.w9)
  • Two adenocarcinomas of the ceruminous gland were seen in a study of 1,525 ferret neoplasias. (B602.9.w9)
  • Vascular neoplasia of the skin/subcutis may be benign or malignant; in either case, complete surgical excision is curative. (B602.9.w9)
  • Both low-grade subcutaneous sarcomas of smooth muscle origin and cutaneous fibrosarcomas have been seen. These low-grade malignant tumours show slow growth and low potential for metastasis. Surgical excision with a wide margin (to ensure complete removal) is usually curative. (B602.9.w9)
    • Cutaneous fibromas and fibrosarcomas have been described in ferrets of 10 months to seven years of age, on the face, neck, axilla and thorax. Fibromas are usually well-demarcated, with well-differentiated fibroblasts in bundles interlaced with various-sized mature collagen bundles, while in fibrosarcomas, differentiation is poorer, nucleoli more prominent and mitotic figures evident. These tumours have not been reported to recur following excision, not to metastasise. (B627.18.w18, J26.30.w3)
      • Vaccination-site fibrosarcomas have been reported. Wide, deep surgical excision is suggested for treatment of fibromas; local radiation therapy might be a useful adjunct. (J213.7.w5)
    • Leiomyosarcoma was seen in a two-year-old female ferret, forming a 3 cm firm, well-demarcated mass on one shoulder. Histopathology showed interwoven or palisading bundles of spindle cells with little stroma.  The abundant cytoplasm was eosinophilic and the oval to spindle-shaped nuclei had a moderately high mitotic index. There was focal necrosis. Cells did not show cross-striation, and were positive for desmin and smooth muscle actin, while being negative for myoglbin, using immunohistochemistry. (B627.18.w18)
  • One squamous papilloma was noted in a study of 1,525 ferret neoplasias. (B602.9.w9)
  • Lipomas of the skin occurred as 5/1525 neoplasias in ferrets in one study. (B602.9.w9)
    • In one ferret, a lipoma formed a well-circumscribed subcutaneous mass, partially encapsulated. Histologically, it was composed of adipose cells, well-differentiated. (B627.18.w18)
  • Six squamous cell carcinomas were seen on the skin of ferrets, in a study of 1,525 ferret neoplasias. (B602.9.w9)
    • Recommended treatment is wide-margin excision, possibly with radiotherapy. Use of bleomycin chemotherapy has been reported. (J213.7.w5)
    • These have been seen in ferrets of 2 - 10 years and in both males and females, forming single or multiple hard nodules or plaques, grey to white. The overlying skin may be alopecic and ulcerated, with fistula formation. On histopathological examination, pearls or islands of keratin are surrounded by sheets, nests and pegs of squamous cells are found, spindle-shaped to polygonal, usually with abundant amphophilic to eosinophilic cytoplasm and large oval nuclei containing one or two prominent nucleoli; there is usually a high mitotic index. In cases with ulceration, inflammatory cells are found in the stroma. (B627.18.w18)
    • Note: these tumours are locally invasive and may metastasise to distant organs as well as to local lymph nodes. Neither surgical excision nor chemotherapy is curative; usually the prognosis is poor. (B627.18.w18)
    • These tumours should be differentiated from tumours of basal cell origin (basal cell tumours, sebaceous cell tumours and baso-squamous-sebaceous cell carcinomas (all of which are usually benign). (B627.18.w18)
  • Two anal sac carcinomas were seen in a study of 1,525 ferret neoplasias. (B602.9.w9)
  • Myxomas or myxosarcomas have been reported rarely in ferrets, forming grey-white, soft, viscoid, poorly-localised masses. Histologically, the tumours are composed of pleomorphic spindle cells in whorls, sheets or lobules together with collagen fibres and basophilic mucinous stroma. (B627.18.w18)
  • Histiocytic neoplasms (malignant fibrous histiocytoma, histiocytoma and malignant histiocytosis) have been seen rarely in ferrets. One malignant fibrous histiocytoma formed a 1.2 cm ulcerated nodule on the lower eyelid of a male ferret, three years of age. Histologically, spindle cells were interwoven with collagen bundles and infiltrated by various macrophages or epitheliod cells, giant cells, lymphocyts and neutrophils. There were foci of ncrosis, haemorrhage and ulceration. (B627.18.w18)
  • A cutaneous polyp was seen as a nodular 3 mm mass on the metatarsus of on a five-year-old female ferret. Histologically, well-differentiated stratified squamous epithelium covered a central fibrovascular core. Neither recurrence nor metastasis was reported. (B627.18.w18, J26.30.w3)
  • Oral neoplasia is seen only occasionally in ferrets, but generally has a poor prognosis. (B602.9.w9)
  • Oral squamous cell carcinoma is aggressive, starting in the gums and invading the underlying bone, with loss of teeth, inappetance and disfigurement. (B602.9.w9)
    • Masses may arise on the lower or upper jaw or palate, be firm or hard and yellow/creamy or pink, and may be ulcerated. The mass may make it difficult for the ferret to eat. Adjacent structures may be destroyed. (B627.18.w18)
    • Histologically, sheets or nests of neoplastic squamous cells are found. (B627.18.w18)
    • Early excision with a wide margin would be the suggested treatment; bleomycin at 20 U/m2 was reported to reduce the tumour mass. (B602.9.w9)
    • Surgical excision and chemotherapy were not successful. (B627.18.w18)
  • Sarcomas such as fibrosarcomas have been reported in ferrets (B602.9.w9, B627.18.w18)and are poorly responsive to treatment. (B602.9.w9)
Salivary Gland
  • Two salivary gland adenocarcinomas have been diagnosed in ferrets. One was noted to be poorly demarcated, with infiltration into adjacent soft tissues including the salivary gland parenchyma. Histologically, acini, nests or trabeculae of cells were found with eosinophilic cytoplasm containing eosinophilic granules, and round to oval nuclei; the mitotic index was high. (B627.18.w18)
Gastro-intestinal tract
  • The commonest GIT tumour is malignant lymphoma, either as a primary or secondary mass. Primary lymphomas have been found particularly in the intestines (9/18 cases of gastrointestinal primary lymphoma in a review), with other sites being the stomach, liver, colon and oral cavity. (B602.9.w9) For further information see Lymphoma in Ferrets
  • Most primary neoplasias of the GIT are malignant. Adenocarcinomas of the GIT (stomach, intestines, rectum) show both local invasion and metastasis to the local lymph nodes. Obstruction of the GIT commonly results from the prominent scirrhous (hardening of tissue) response. The same response however, may contain the growth, and assists with visualisation of the neoplasm, facilitating complete surgical excision. Prognosis is highly dependent on whether or not the tumour has metastasised at the time of surgery. (B602.9.w9)
    • Gastric adenocarcinomas in ferrets develop around the pylorus - the region where Helicobacter mustelae colonises most heavily. 
    • With pyloric adenocarcinoma, vomiting, lethargy, anorexia, dehydration, weight loss and bloated abdomen may develop (as with gastric obstruction). (B627.18.w18, J213.7.w5) Radiographically, the stomach may be obviously distended or obstructed. (B627.18.w18, J213.7.w5) 
      • Surgical resection has been attempted unsuccessfully. (J213.7.w5)
      • Grossly there is gastric dilatation, pyloric stenosis and thickening or replacement of the pyloric wall with firm or friable, solid or cystic and fibrous and/or gritty discrete irregular masses, up to 2-3 cm diameter. Histologically, in the pyloric mucosa, submucosa and muscle layers, foci of pleomorphic gastric epithelial cells, arranged in cords, nests, acini or cysts are found, sometimes with mucinous metaplasia of the cells and fibroplasia of the stroma; in some cases, the stroma showed osteoid metaplasia. Helicobacter mustelae may be found in the gastric mucosa. Metastases may be present in the local lymph nodes and portal vein. (B627.18.w18)
    • Intestinal leimyoma or leiomyosarcoma may be treated by excision; the rate of recurrence is unknown. A case of successful treatment by excision followed by doxorubicin (five treatments at intervals of three weeks) was reported. (J213.7.w5)
    • Squamous cell carcinoma of the anus has been described. (B627.18.w18)
  • Insulinomas (Islet cell tumours) are common in ferrets. See: Insulinoma in Ferrets
  • Neoplasia of the exocrine pancreas is not common. When such tumours do occur they tend to be locally aggressive but not metastatic, therefore if detected early, complete surgical excision may be useful. (B602.9.w9)
    • Pancreatic adenomas may be incidental findings in asymptomatic ferrets. Grossly, the well-circumscribed nodules may be single or multiple, round to oval and grey to tan. Histologically, cells appear similar to normal acinar cells and may be found in sheets or arranged into acini. (B627.18.w18)
    • Pancreatic adenocarcinomas have been found in male and female ferrets 2-10 years old, and were usually aggressive. Lethargy, anorexia and abdominal distension were the presenting signs, with widespread abdominal masses (not just in the pancreas) detected by palpation or radiography, and variable peritoneal effusion. Grossly, there were variable numbers of masses in the pancreas, firm to friable and variable in size but up to 3 cm. Sometimes there were also masses in the diaphragm, mesentry, omentum, abdominal wall and gastrointestinal wall; in some, complete organs were replaced by the neopastic tissue. Serosanguinous fluis was presnt in some ferrets. Histologically, sheets, acini, trabeculi or tubules of pleomorphic epithelial cells were separated by various quantities of fibrovascular stroma. The cuboidal to culumnar cells had scant to abundant eosinophilic cytoplasm and hyperchromatic nuclei with large, prominent nuclei and variable mitotic index. In some poorly differntiated tumours, cyst formation, osseous metaplasia and necrosis were present. Metastases to regional lymph nodes and to the lungs were also found. (B627.18.w18)
  • When pancreatic adenocarcinoma has occurred in ferrets, carcinomatosis (seeding over the peritoneal cavity) has developed. The prognosis is poor and chemotherapy is unlikely to be effective. (J213.7.w5)
  • Hepatic neoplasia generally causes weight loss, anorexia and lethargy, with palpation revealing a cranial abdominal mass (or this may be detected by radiography. Usually, clinical pathology findings are nonspecific with only mild abnormalities present. All hepatic neoplasms should be biopsied. Lobectomy is the treatment of choice for masses involving a single lobe. (B602.9.w9)
    • Histopathological characteristics distinguish benign from malignant hepatic tumours. (B627.18.w18)
  • In a study of 1,525 ferret neoplasias, 25 primary hepatic neoplasias were found (17 biliary cystadenoma/cholangioma, two cholangiocarcinomas, two hepatomas and two hepatocellular carcinomas), as well as 71 metastases of tumours from other sites with 48 being associated with malignant lymphomas, 11 with adrenocortical carcinoma and 10 with adenocarcinomas of unspecified primary origin). (B602.9.w9)
    • Increases in hepatic enzymes are consistently found with both hepatocellular carcinoma and cholangiocarcinoma; both lead to eventual liver failure; other signs are profound anaemia, ascites and haemoperitoneum. (B602.9.w9)
    • Ferrets with hepatocellular carcinoma showed lethargy, anorexia and weight loss. The liver was greatly enlarged (as much as 4 - 5 times normal size), with the parenchyma containing various sizes of white or grey nodules. Histologically, acini, sheets or cords of large cuboidal to pleomorphic cells were found. There may be metastases in the mesenteric lymph node and the spleen. (B627.18.w18)
    • Biliary cystadenomas (histologically benign) and malignant forms may grow aggressively to take over a liver lobe and result in liver failure. (B602.9.w9)
      • Histologically in biliary adenomas, acini or tubules of pleomorphic cells have been found, with a low mitotic index. In a biliary adenocarcinoma, the pleomorphic biliary epithelial cells were arranged in irregular acini, lobules and glands, and the mitotic index was high. (B627.18.w18)
    • Biliary cystadenomas are benign neoplasms; they are cystic and multilobulated with masses being 1.5 cm to 8x7x7 cm, replacing the normal liver parenchyma. The spherical or oval cysts, containing thin clear or straw-coloured fluid and with irregular fibrous capsules, are interconnected. Some cysts have thicker contents. Histologically, cuboidal to columnar epithelial cells are arranged in a single layer in each cyst, surrounding clear to eosinophilic secretions, and with a thin fibrous stroma; there may be infoldings or papillary growths into some cysts. A variable quantity of pale to eosinophilic cytoplasm is present; the nuclei are basal or central. In biliary cystadenomas, cells are more pleomorphic, with some mitotic figures present, and may be locally invasive. (B627.18.w18)
  • Lobectomy or a wide surgical margin is important for any cystic neoplasm, because biliary cystadenomas are aggressive. (B602.9.w9)
    • Often, multiple tumours emerge and replace the normal hepatic tissue. (J213.7.w5)
  • Note: Doxorubicin treatment of two ferrets with diffuse hepatocellular carcinoma was unsuccessful. (J213.7.w5)
  • In populations of ferrets in which neutering is commonly performed (e.g. USA), reproductive tract tumours are uncommon. (B602.9.w9)
  • Ovarian tumours may produce no clinical signs, or be noticed only due to reproductive failure. (B602.9.w9)
  • Testicular tumours may result in aggression, prominent male odour, and a greasy, poor hair coat as well as sexual behaviour in an apparently castrated male (when occurring in a male with a retained testis). (B602.9.w9)
  • Ovarian and uterine tumours in a study were mainly of smooth muscle origin (leiomyoma, leiomyosarcoma); surgical excision was curative even with tumours which appeared malignant based on histopathological appearance (no evidence of metastasis). (B602.9.w9)
  • Primary gonadal (ovarian) tumours recorded in a study included granulosa cell tumours (four), teratomas (four), Leydig cell tumours (three) and sex cord stromal tumours (two). Most ovarian tumours were found incidentally at the time of neutering. (B602.9.w9)
    • Teratomas may become large and be detected on routine clinical examination (palpation). Bone in teratomas may be detected on radiographs. (B602.9.w9)
    • One ovarian Leydig cell tumour showed metastasis to a lymph node. (B602.9.w9)
  • Primary testicular tumours in a review were most common in retained testes and included Leydig cell tumours (seven), seminomas (five), Sertoli cell tumours (four, one with metastasis to the liver) and carcinoma of the rete testis (one). Multiple neoplasms were sometimes present. (B602.9.w9)
  • Testicular interstitial cell tumours have been seen in ferrets of 3 - 7 years old, causing enlarged testes, and found in an undescended testis. They secrete androgens. Affected testes were large (up to 3 x 2 x 2 cm), firm and pale to yellowish, either nodular or multinodular in appearance sometimes with mottling or haemorrhagic cysts. Histologically, irregular lobules, nests or sheets of neoplastic cells separated by fibrovasuclar stroma were found. The oval or polygonal cells had a variably abundant, eosinophilic, foamy or vacuolar cytoplasm and a round to oval, hyperchomic, variably-sized nucleus with a single nucleolus; the mitotic index was generally low. Blood and/or proteinaceous material filled scattered polycystic spaces. In some masses there was haemorrhage and/or necrosis. Metastatis was not reported in any case. (B627.18.w18)
  • Sertoli cell tumours in males of 4.5 - 6 years caused unilareral or bilateral testicular enlargement. Grossly, the tumours were white, solid and firm. Histologically, oval to spindle-shaped cells were found in tubules and/or sheets, with fibrous septa. There was variable atrophy of the seminiferous tubules in adjacent areas. (B627.18.w18)
  • A seminoma has been seen in a 4.5-year-old male ferret forming a soft, friable mass. Histologically, cells with large round nuclei were either arranged irregularly within tubules or were surrounded by fibrous bands. There was a low mitotic index. There was atrophy of seminal tubules adjacent to the tumour. (B627.18.w18)
  • Ovarian leiomyomas in female ferrets from 1.5 - 7 years of age  have been single or multiple solid opaque/white (compared with the pink-grey normal ovarian tissue) nodules up to 1.8 cm diameter. Histologically, they were composed of smooth muscle cells. A leiomyosarcoma showed slightly pleomorphic cells and a low mitotic index. (B627.18.w18)
  • Fibromyoma (bilobed, one lobe 5 mm, the second lobe 10 mm) and fibroleiomyoma (2 cm) were found in two females; they were firm and pink-white on the cut surface. Histologically, smooth muscle cell bundles, fibroblasts and bands of fibrous tissue were present. (B627.18.w18)
  • Bilateral ovarian fibromatoid tumous seen in one ferret were bilateral hard glistening masses 9mm and 16 mm. Histologically, spindle cells were found in dense bundles or whorls. (B627.18.w18)
  • A papillary adenocarcinoma has been seen on the ovary, Histologically, irregular fibrous bands separated multicyctic structures, with cuboidal to columnar cells lining the multibranched cysts or acini; there were multifocal papillary infoldings. (B627.18.w18)
  • Thecomas (benign ovarian stromal cell tumours) have been seen rarely as firm, smooth, lobulated masses, as large as 14 x 11 x 11 mm, with a solid yellow homogenous cut surface. Histologically, interlaced bundles of pleomorphic spindle cells and clusters of (or individual) oval cells with foamy/lipid-containing cytoplasm were seen. (B627.18.w18)
  • Rare tumours include uterine adenocarcinoma and uterine deciduoma. (B602.9.w9)
  • Uterine teratoma has been described as a palpable mass on the right uterine horn, with a gritty, cyctic cut surface, the cysts containing brown to green thick fluid. Histologically, a variety of tissues from all three germ layers could be identified. (B627.18.w18)
  • Uterine fibroma was seen in a four-year-old ferret. Histologically, the tumour was made up of spindle cells (well-differentiated fibroblasts) and mature bundles of collagen. (B627.18.w18)

Mammary gland

  • Papillary cystadenocarcinoma has been seen in female domestic ferret and in a female Mustela nigripes - Black-footed ferret. In the black-footed ferret, the tumour metastasised to the liver and spleen as well as to iliac and mesenteric lymph nodes. Histologically various shapes and sizes of acini, ducts and tubules were formed from pleomorphic cuboidal to columnar cells. (B627.18.w18)
  • A mixed mamary gland tumour was seen in a seven-year-old female ferret. Histologically, pleomorphic epithelial cells were arranged in tubules and acini, with abundant fibrous stroma, mainly surrounded by a bluish matrix and proliferative myoepithelial cells. (B627.18.w18)
  • Skeletal tumours are not uncommon and are generally easily visible. (B602.9.w9)
  • Skeletal muscle tumours are rare. (B602.9.w9)
    • One rhabdomyosarcoma was recorded in a study of 1524 ferret neoplasias. (B602.9.w9) three other cases have been reported. (B627.18.w18)
    • Radical excision can be curative but is not always practical. (B602.9.w9) 
  • In a review of 1,524 ferret tumours, chordomas made up 79% of musculoskeletal tumours. These usually occur at the tail tip, causing a clublike irregularly round grey-white firm swelling (they can arise elsewhere on the spine). The locally invasive tumours are both lytic and proliferative, and destroy the vertebral body of the affected vertebra, but rarely metastasise. 
    • When chordomas occur at the tail tip, amputation is usually effective. (B602.9.w9)
      • Amputation should be performed several vertebrae proximal to the tumour. (J213.7.w5)
    • Chordomas occurring elsewhere on the spine have a poor prognosis; (B602.9.w9) pathological fracture of the affected vertebra  occurs as the disease progresses, and euthanasia is required. (B631.30.w30)
      • With cervical chordoma, ferrets have presented with posterior paresis and ataxia. (J213.7.w5)
      • Surgical resection might be attempted. (J213.7.w5)
  • Osteomas and osteosarcomas occur occasionally in ferrets. (B602.9.w9)
    • Osteomas are slow-growing and are well-circumscribed. (B627.18.w18)
    • Osteomas present with signs relating to the displacement or compression of adjacent structures. (J213.7.w5)
      • Histologically, these contain compact lamellar bone and bony trabeculae, with mild to moderate osteoblastic and haemolytic activity. (J213.7.w5)
      • Slowly-progressive osteomas of flat bones, including the skull and ribs, may occasionally be excised successfully, but generally recur at the same site. (B602.9.w9)
      • Complete surgical excision of osteomas is curative. (J213.7.w5)
    • Osteosarcomas, of flat bones or long bones, are rare; they are locally destructive. (B602.9.w9) Note: diagnostic biopsies which do not include the core of the lesion may only contain the overlying periosteal reaction and therefore produce an erroneous diagnosis. (B602.9.w9)
      • For osteosarcoma, amputation is the treatment of choice (if practical). (B602.9.w9, J213.7.w5)
      • Note: Ferrets generally cope very well following limb amputation. (J213.7.w5)
  • Chondromas and chondrosarcomas arising from flat bones are rare. (B602.9.w9)
  • Chondromas have been reported arising from the intervertebral cartilage. These are well, differentiated and histologically similar to normal cartilage. (B627.18.w18)
  • An intraosseous liposarcoma was found in the marrow of the mandible of a two-year-old male ferret. (B627.18.w18)
  • One synovial cell sarcoma has been described, in a two-year-old male ferret, forming a 4 x 4 x 6 cm mass around the stifle joint. Epithelial cells were found in sheets, clefts and clusters separated by fibrous stroma; the cells stained dark, with the cytoplasma occasionally vacuolated, and pleomorphic nuclei with a high mitotic index; there were also giant cells. The cells invaded the periosteum, bone and subcutis. (B627.18.w18)
Central nervous system (CNS)
  • CNS tumours are rare in ferrets. In a study of 1,525 tumours of ferrets, five CNS tumours were detected, including three astrocytomas, one granular cell tumour and one meningioma. Nevertheless, they are the third most common cause of neurological signs (insulinomas and bacterial meningitis/encephalitis being the first two). CNS neoplasia should be considered when the commoner causes have been ruled out. Signs are often nonspecific and may be lateralised. (B602.9.w9)
    • A granular cell tumour (myoblastoma) was found in the middle right forebrain of a ferret presenting with intermittent and progressive head tilt (right), circling 9right), ataxia, torticollis and seizures. It was off-white, oval and well demarcated; the overlying cerebral cortex showed loss of sulci and broadening of gyri. Histologically, large round to polygonal cells were present in sheets, with little stroma. The cells contained abundant pale/eosinophilic granular cytoplasm (PAS-positive and diastase-resistant granules) and small dark nuclei, eccentrically placed and round to oval with occasional small single nucleoli seen. (B627.18.w18)
Peripheral nervous system
  • Peripheral nervous system tumours are rare. Peripheral nerve sheath neoplasms may be benign or malignant. They are generally found in the skin and subcutis, often on the head, including the eyelid. Malignant tumours show rapid growth with local invasion. Complete excision, where possible, is curative; several surgical operations may be required. (B602.9.w9)
  • Schwannoma (of the perineural cells) is generally benign and usually found in the skin (others in ferrets have been found in th adrenal gland, the abdomen and the neck (vagus nerve)) (B602.9.w9, B627.18.w18) and excision at an early stage is recommended to assist in closure of the resultant skin defect. (B602.9.w9)
  • Ganglioneuromas are rare, benign and usually asymptomatic (B602.9.w9, B627.18.w18). A ganglioma adjacent to the adrenal gland may be misdiagnosed as an adrenal tumour on gross examination. (B602.9.w9)
Urinary system
  • Ferrets rarely develop urinary tract neoplasia. (B602.9.w9)
  • The most commonly seen urinary tract neoplasia of ferrets is renal transitional cell carcinoma. There do not metastasis but can cause outflow obstruction and subsequent hydronephrosis. Unilateral nephrectomy should be curative if the mass is detected early. (B602.9.w9)
  • Renal carcinomas have been reported. They are usually slow-growing with a low metastatic potential and are detected only at necropsy, although they may also be visualised ultrasonographically as cystic areas similar to renal cysts. Occasioally these result in haemoperitoneum and require emergency unilateral nephrectomy. (B602.9.w9)
  • Renal adenomas have been reported. They are usually slow-growing with a low metastatic potential and are detected only at necropsy, although they may also be visualised ultrasonographically as cystic areas similar to renal cysts. (B602.9.w9)
  • Bladder transitional cell carcinomas have been reported and carry a poor prognosis. The presenting signs are vague, with dysuria and incontinence likely to be diagnosed as crystalluria or cystic prostatic disease, therefore extensive local invasion is likely to have occurred prior to diagnosis. Surgical biopsy is required for definitive diagnosis. (B602.9.w9)
  • A renal pelvis transitional cell carcinoma was seen in a female ferret. The ferret had been lethargic, anorexic and losing weight. Initial diagnosed by palpation was confirmed by radiography. The lobulated tumour, 10 cm diameter, which had replaced the kidney, was removed. Histologically, papillae, lobules, cysts and tubules of cells were present. (B627.18.w18)
  • A papillary tubular cystadenoma was an incidental necropsy finding in a female ferret. It was 3 cm in diameter and cystic. Histologically, tubular, cystic and papillary patterns of neoplastic cells were present. (B627.18.w18)
Respiratory system
  • One primary lung neoplasm has been reported. More commonly, tumours found in the lung are metastases from other sites. In lymphoma with pulmonary metastasis, chemotherapy may be useful. (B602.9.w9) See Lymphoma in Ferrets
  • The main type of tumour is adenoma/adenocarcinoma (adrenocortical cell neoplasms). See: Adrenocortical Neoplasia in Ferrets
  • Adrenal gland teratomas have been reported, bilaterally in one ferret, unilaterally in another. Clinical signs in the ferret with unilateral teratoma included weight loss, anorexia and progressive weakness, with a mass cranial to the right kidney. Gross necropsy showed a 2 x 2.5 x 1.3 cm hard adrenal gland, its surface granular and brown to yellow, adhering to the caudate lobe of the liver. On incision, compressed adrenal tissue was revealed surrounding an oval bony cystic mass with a 2-5 mm thick incomplete bony shell containing yellow fluid, and hair shafts. In the other ferret the teratomas were 2.5 - 3 cm diameter. Histopathology revealed absent or compressed adrenal tissue while the tumour was composed of multiple tissues derived from three germ layers, including e.g. bone, in one case a rudimentary tooth, tooth, cartilage, squamous epithelia, skin, hair, keratin and sebaceous and apocrine glands. (B627.18.w18)
  • Adrenocortical spindle cell tumours have been seen with or without concurrent adrenocortical cell neoplasia, affecting intact and neutered male and female ferrets of 3 - 7 years of age. Variable numbers of spindle cells were found in the adrenal cortex, with small amounts of amphophilic cytoplasm and oval to elongated nuclei. (B627.18.w18)
  • Phaeochromatomas have been found in ferrets with lethargy and tachycardia. Grossly, masses were present cranial to the kidney, often being around the caudal vena cava. Histologically, the cells, arranged in small lobules, nests, palisades or trabeculae around the capillary or sinusoids were cuboidal and polyhedral to columnar with pale to amphophilic cytoplasm and hyperchromatic nuclei with only few mitotic figures. (B627.18.w18)
  • Thymomas form cystic masses in the cranial mediastinum, resulting in lethargy, chronic episodic vomiting, and dyspnoea and wheezing in ferrets. Radiographically, they appear similar to mediastinal lymphoma. Ultrasound-guided fine needle aspirate biopsy followed by cytology should be diagnostic. They may be surgically excised if not too large; radiotherapy may be considered with a large tumour to reduce its size and permit excision. (J213.7.w5)
Thyroid gland
  • Thyroid gland adenomas and adenocarcinomas are rare. Thyroid gland adenomas may be present without clinical disease. A ferret with thyroid adenocarcinoma showed dysphagia. Grossly, the adenomas were 2-3mm unilateral well demarcated masses each with an incomplete thin fibrous capsule. Histologically, arrangements of cuboidal to high columnar cells were present forming acini and cysts with only little stroma, and containing eosinophilic material. Pale to eosinophilic, often abundant cytoplasm, and round to oval nuclei with few mitotic figures were seen. Follicular epithelial cells adjacent to the masses were atrophic. (B627.18.w18)
  • In a study, 12% of 1525 neoplasias in ferrets were vascular, mainly in the skin or subcutis. Many were considered malignant, based on histopathology, but metastasis was rare. When found associated with the skin, excision is generally curative. However, haemangiosarcomas of abdominal organs (reported in the liver, spleen pancreas and lymph node, as well as free-floating in the abdomen) tend to grow aggressively and may rupture with resultant fatal haemorrhage or seeding of the abdomen with metastases. If the tumour is still restricted to a single site and can be excised, this would be the treatment of choice. (B602.9.w9)
    • Other than the skin, the liver is the most common site; they also occur occasionally in the spleen and rectum. (B627.18.w18)
    • Sudden unexpected death has been a common presentation with these tumours in the liver; haemopetitoneum has been a common finding. (B627.18.w18)  
    • The prognosis with haemangiosarcoma of the liver or spleen is poor. (J213.7.w5)
    • Haemangiomas/haemangiosarcomas on the skin of ferrets have occurred in the lumbar area, on the ear pinna and at the commissure of the lips. (J26.30.w3)
      • In ehte skin, these appear as small dark red/black masses. Histologically, masses in the dermis were composed of well-differentiated endothelial cells around blood-filled spaces. The tumour on the lip was 1x1 cm, fluid filled and poorly demarcated; histologically sinusoidal spacs were formed by spindle-shaped to polygonal cells. (B627.18.w18)
    • In the hepatic site, single to multiple nodules 2 - 20 mm diamater and dark red in coulour may be within the liver parenchyma or raised. Blood-filled spaces are lined with a single layer of differentiated endothelial cells and surrounded by fibrous stroma/septa. In haemangiosarcomas, masses are large and irregular with anaplastic endothelial cells around blood-filled clefts, and extension into adjactent sinusoids. Both local invasion and metastasis have been seen. (B627.18.w18)
  • In a study, 48/1,525 ferret tumours were of these types. They have a low metastatic potential, although they can grow quite large. When found on the skin (arising from smooth muscle associated with hair follicles), surgical excision is curative. Those of the adrenal gland capsule may both be mistaken for adrenal neoplasia and may mask such tumours. (B602.9.w9)
Plasma cell myeloma
  • This has been reported. (J213.7.w5)
Peritoneal mesothelioma
  • Two cases have been reported, with no treatment attempted in one case and unsuccessful surgical resention in the other. (J213.7.w5)
Further Information
  • Neoplasms have been detected in ferrets of all ages from just a few months old to 15 years and older, but peaking at four to six or seven years of age. (B602.9.w9, B627.18.w18)
  • Neoplasia has been detected in males and females about equally, but more in neutered (spayed or castrated) than in entire ferrets. (B627.18.w18)
  • Clinical examination is useful for detection of external masses visually or by palpation, and for palpation of some internal masses. Coughing, breathing difficulties and auscultation also may be useful in indicating masses in the thorax. (B631.30.w30)
  • Clinical examination findings and radiography are not sufficient for diagnosis, which requires cytological and/or histopathological examination of an adequate sample, with excisional biopsy preferable to incisional biopsy samples. (J213.7.w5)
  • Cytological examination of a fine-needle aspirate may distinguish between normal tissue, a benign tumour and a malignant tumour, but histopathological examination generally is needed for definitive diagnosis. Histopathological examination also allows the tumour's growth pattern and architecture to be examined, which is not possible with cytological specimens from aspirated material. (B631.30.w30, J213.7.w5)
  • Detection of very high lymphocyte counts (e.g. 20,000/ÁL) is associated with lymphoma; moderately high counts may indicate lymphoma but can occur with some infectious processes. (J213.7.w5)
  • Immunohistochemistry can be used for identifying cellular origin, for example to distinguish between B-cell and T-cell lymphomas (with CD3 udes as a T-ell marker and CD79a as a B-cell marker). (B631.30.w30, J213.7.w5)
  • Diagnosis of the tumpour type or cellular origin is difficult with undifferentiated or anaplastic tumours. (J213.7.w5)
  • Radiography can be useful particularly for the detection of metastases and for monitoring of responses to treatment (e.g. reduction in liver size). Radiography generally gives poor discrimination between normal soft tissue and neoplastic soft tissue; it does not distinguish between neoplastic and normal tissues with the same density and is not useful for assessment of invasiveness or tissue architecture. (J213.7.w5)
    • Thoracic radiography is used for detection of lung metastases as well as mediastinal masses.
  • Ultrasonography gives less defined spatial resolution than does radiography, but is able to give more data or architecture and size of lesions. (J213.7.w5)
    • Ultrasonography is particularly useful for location of abdominal masses and may be useful in defining the extent of mediastinal masses. (B631.30.w30)
  • Endoscopy can be very useful for examining inside the lumen of the upper respiratory tract, stomach and colon. Rigid endoscopy with air insufflation can be used to visualise most of the abdominal organs. (J213.7.w5) 
  • CT and MRI also can be useful, (B631.30.w30, J213.7.w5) while scintigraphy is particularly useful for early detection of metastases in bone. (J213.7.w5)
  • Depending on the tumour, surgery, chemotherapy, radiation therapy or combinations of these may be used. (B631.30.w30, J213.7.w5)
    • Chemotherapy generally leads to remission for a period of time, but is not curative. (B631.30.w30)
    • Both intralesional and systemic chemotherapy may be used. (B631.30.w30)
    • Glucocorticoids can be used instead of chemotherapy; this treatment is usually effective for a relatively short period of time. (B631.30.w30)
    • Where complete surgical removal of a tumour is not possible, debulking may still be useful as a palliative measure. (B631.30.w30)
  • Supportive treatment must be provided alongside specific therapy. This includes optimal feeding, which may require placement of an oesophageal feeding tube to allow administration of a high-quality liquid feline convalescent diet. (B631.30.w30)
Associated Techniques
Host taxa groups /species  
Author Dr Debra Bourne MA VetMB PhD MRCVS (V.w5)

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