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==Introduction==

==Introduction==

Ferrets (''Mustela putorius furo'') are thought to have been dometicated for over 2000 years and are descended from the wild European Polecat. Despite being domesticated for such a long period, ferrets were only recognised as important in medical research in the 20th century and were only beginning to be used in the 1960s as an important animal model. Ferrets are often utilised in a laboratory setting as they are known to share many anatomical, metabolic and physiological features with humans. Therefore ferrets are often utilised in studies covering a broad subject matter including toxicology, bacteriological and virological studies. Ferrets have also been used as a model for studies into ischemia and ion exchange in the heart, influenza, neurological injury and gastric infections. Ferrets are particularly important in influenza studies as they can be infected with type A and B influenza viruses. According to the US Department of Agriculture Animal Care Report, approximately 17,000 ferrets were used in laboratory studies.  

Ferrets (''Mustela putorius furo'') are thought to have been dometicated for over 2000 years and are descended from the wild European Polecat. Despite being domesticated for such a long period, ferrets were only recognised as important in medical research in the 20th century and were only beginning to be used in the 1960s as an important animal model. Ferrets are often utilised in a laboratory setting as they are known to share many anatomical, metabolic and physiological features with humans. Therefore ferrets are often utilised in studies covering a broad subject matter including toxicology, bacteriological and virological studies. Ferrets have also been used as a model for studies into ischemia and ion exchange in the heart, influenza, neurological injury and gastric infections. Ferrets are particularly important in influenza studies as they can be infected with type A and B influenza viruses. According to the US Department of Agriculture Animal Care Report, approximately 17,000 ferrets per year are used in laboratory studies.  

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==Strains and Stocks==

==Strains and Stocks==

Most ferrets utilised for laboratory studies are males due to oestrous related health problems associated with females. Female ferrets are induced ovulators and can develop severe hyperoestrous if not mated. Laboratory ferrets are often purchased pre-castrated and 'de-scented' (i.e. anal gland sacculectomy).  

Most ferrets utilised for laboratory studies are males due to oestrous related health problems associated with females (see Reproductive disease section below). Female ferrets are induced ovulators and can develop severe hyperoestrous if not mated. Laboratory ferrets are often purchased pre-castrated and 'de-scented' (i.e. anal gland sacculectomy).  

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Due to the small number of laboratory ferrets compared to species such as mice, there are no specific strains/stocks commonly used. Researchers often request natural wild-type colour patterns (called sable or fitch) which is often in contrast with the various coat colour variations found in domestic populations. Some studies have also utilised albino ferrets.   

Due to the small number of laboratory ferrets compared to species such as mice, there are no specific strains/stocks commonly used. Researchers often request natural wild-type colour patterns (called sable or fitch) which is often in contrast to the various coat colour variations found in domestic populations. Some studies have also utilised albino ferrets due to their specific genetic properties.   

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==Physiology==

==Physiology==

Most physiological data for ferrets is very similar to that of the domestic cat. Ferrets are obligate carnivores that typically have a total length of ~50cm (with a ~13cm tail) and weight between 0.7 - 2kg. Ferrets have a natural life span of between 7 - 10 years and males are substantially larger than females, with males up to 2kg and females up to 1.2kg. Ferrets become sexually mature at around 4-6 months and occurs in the first spring after birth.

Most physiological data for ferrets is very similar to that of the domestic cat. Ferrets are obligate carnivores that typically have a total length of ~50cm (with a ~13cm tail) and weight between 0.7 - 2kg. Ferrets have a natural life span of between 7 - 10 years and males are substantially larger than females, with males up to 2kg and females up to 1.2kg. Ferrets become sexually mature at around 4-6 months, usually occurring in the first spring after birth.

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Gross lesions will be similar to those found in canines. Animals will suffer photophobia (excessive sensitivity to light). Gross lesions will include oculonasal discharge, hyperkaratosis of the planum nasale and footpads, papular rashs around chin and bronchopneumonia. Microscopic lesions will include brightly eosinophilic intracytoplasmic and intranuclear inclusions often in epithelial cells, neurons, WBCs and megakaryocytes. (Studies have shown that the biliary epithelium, urinary bladder and renal pelvis are the most productive places to look for these inclusions. A non-suppurative encephalitis with de-mylination may also be seen.

Gross lesions will be similar to those found in canines. Animals will suffer photophobia (excessive sensitivity to light). Gross lesions will include oculonasal discharge, hyperkaratosis of the planum nasale and footpads, papular rashs around the chin and bronchopneumonia. Microscopic lesions will include brightly eosinophilic intracytoplasmic and intranuclear inclusions often in epithelial cells, neurons, WBCs and megakaryocytes. (Studies have shown that the biliary epithelium, urinary bladder and renal pelvis are the most productive places to look for these inclusions. A non-suppurative encephalitis with de-mylination may also be seen.

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Gross lesions will include bilaterally symmetrical alopecia beginning over the tailhead and progressing cranially over the flanks and abdomen. The presence of an enlarged vulva in a spayed female is also strongly suggestive of AAE. The normal length of ferret adrenal glands is 3-5mm. Glands exceeding 5mm will often contain proliferative lesions. Diameters exceeding 1cm is highly suggestive of adrenocortical carcinoma. Microscopic lesions will include proliferative lesions within the adrenal cortex that can be catagorised into three stages; hyperplasia, adenoma and carcinoma. The presence of necrosis, cellular atypia and a high mitotic rate are suggestive of malignancy. The presence of a single nodule within the adrenal cortex without any other factors associated with cancer may indicate adenoma. The presence of multiple nodules without any other factors associated with cancer may indicate cortical hyperplasia.  

Gross lesions will include bilaterally symmetrical alopecia beginning over the tailhead and progressing cranially over the flanks and abdomen. The presence of an enlarged vulva in a spayed female is also strongly suggestive of AAE. The normal length of ferret adrenal glands is 3-5mm. Glands exceeding 5mm will often contain proliferative lesions. Approximately 45% of these will be carcinomas, 45% will be hyperplasia and 10% adenomas. Diameters exceeding 1cm is highly suggestive of adrenocortical carcinoma. In cases of adrenal malignancy, metastasis often occurs late in the course of the disease and ferrets are more likely to die from vascular haemorrhage as a result of tumor necrosis in a large adrenal malignancy rather than as a result of metastatic disease. Microscopic lesions will include proliferative lesions within the adrenal cortex that can be catagorised into three stages; hyperplasia, adenoma and carcinoma. The presence of necrosis, cellular atypia and a high mitotic rate are suggestive of malignancy. The presence of a single nodule within the adrenal cortex without any other factors associated with cancer may indicate adenoma. The presence of multiple nodules without any other factors associated with cancer may indicate cortical hyperplasia.  

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'''Lymphosarcoma'''

'''Lymphosarcoma'''

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Lymphosarcoma is the most common form of malignancy in ferrets. These neoplasms usually arise spontaneously, although recently some degree of horizontal transmission has been suggested. There are several variants of lymphoma in ferrets. The most common form is where the neoplastic cell is a mature, well-differentiated lymphocyte primarily resulting in peripheral lymphadenopathy with visceral spread and a subsequent organ failure. This form usually occurs in older ferrets. A second form of lymphoma that usually occurs in younger ferrets is where the neoplastic cell is a large blastic lymphocyte characterised by early by early visceral neoplasms and is almost always concurrent with the production of a large thymic mass. A third uncommon form is characterised by combinations of peripheral lymphadenopathy, visceral neoplasms and numerous bizarre lymphoblasts. This third form is known as the immunoblastic polymorphous variant.  

Lymphosarcoma is the most common form of malignancy in ferrets. These neoplasms usually arise spontaneously, although recently some degree of horizontal transmission has been suggested. There are several variants of lymphoma in ferrets. The most common form is where the neoplastic cell is a mature, well-differentiated lymphocyte primarily resulting in peripheral lymphadenopathy with visceral spread and a subsequent organ failure. This form usually occurs in older ferrets. A second form of lymphoma that usually occurs in younger ferrets is where the neoplastic cell is a large blastic lymphocyte characterised by early visceral neoplasms and is almost always concurrent with the production of a large thymic mass. A third uncommon form is characterised by combinations of peripheral lymphadenopathy, visceral neoplasms and numerous bizarre lymphoblasts. This third form is known as the immunoblastic polymorphous variant.  

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'''Dental Disease'''

'''Dental Disease'''

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Broken teeth are common in older ferrets, particularly the upper canines. If the tooth pulp is exposed, extraction or root canal procedures are required. Accumulation of dental calculi is also common in older animals. Tooth root abscesses are common in ferrets as well as dental malformations including supernumerary teeth.

The two most common dental diseases of ferrets are periodontal disease and fractured teeth (common in older ferrets), particularly the upper canines. In fractured teeth, if the tooth pulp is exposed, extraction or root canal procedures are required. Tooth root abscesses are common in ferrets as well as dental malformations including supernumerary teeth. Periodontal disease can present (rarely) in immunosuppressed animals such as those on long-term immunosuppressive drugs. Accumulation of dental calculi is also common in older animals.

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Gross lesions will include discolouration of broken teeth which suggests devitalisation.

Gross lesions for damaged teeth will include discolouration of broken teeth which suggests devitalisation.

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== Other  ==

== Other  ==

'''Cataracts''' <br> No definitive cause has been found for cataracts in ferrets and many cases are thought to be spontaneous. Cataractous chnages may also be seen in diabetic animals but often due to the short life span of ferrets, grossly visible cataracts are not common. <br> <br> Gross lesions will involve both the cortex and nucleus of the lens. Microscopic lesions will include the formation of balloon cells in the outer cortex initially, then progressing towards the nucleus of the lens. <br> <br> '''Neoplasia (Other than described above)''' <br> Neoplasms represent approximately 60% of surgical biopsies in ferrets with the majority being islet cell tumors, adrenal neoplasms, chordomas and skin tumors, all mentioned in the relevant sections above. There are others that are worth mentioning here. <u>Testicular neoplasms</u> are usually interstitial cell tumors and are often a combination of two or more neoplasms. The removal of cryptorchid testicles is very important in ferrets as at least one one neoplasm will always be found on a retained testicle. <u>Ovarian neoplasms</u> are tumors of germ cells or stromal cells. The second most commonly seen neoplasms are <u>Gastrointestinal neoplasms</u>. These are usually tumors of smooth muscle origin. Low-grade leiomyosarcommas are most commonly seen although mesotheliomas are sometimes seen in the peritoneum and serosal surfaces of ferrets. These mesotheliomas are locally aggressive and will result in marked abdominal effusion and often have a poor prognosis. <u>Pancreatic exocrine adenocarcinomas</u> are also found and these are also locally aggressive neoplasms. Within the musculoskeletal system, <u>Osteomas</u> have also been reported, arising from flat bones. These are expansile neoplasms composed of trabecular, well-differentiated bone and lined by osteoblasts. <u>Apocrine cysts</u> are also a common finding within the integumentary system of ferrets. These most commonly occur around the head, neck, prepuce and vulva due to the large number of scent glands in these areas. Apocrine gland carcinomas are also not uncommon and have a similar distribution. Apocrine carcinomas are locally aggressive neoplasms with a moderate potential for metastasis.

'''Cataracts''' <br> No definitive cause has been found for cataracts in ferrets and many cases are thought to be spontaneous. Cataractous changes may also be seen in diabetic animals but often due to the short life span of ferrets, grossly visible cataracts are not common. <br> <br> Gross lesions will involve both the cortex and nucleus of the lens. Microscopic lesions will include the formation of balloon cells in the outer cortex initially, then progressing towards the nucleus of the lens. <br> <br> '''Neoplasia (Other than described above)''' <br> Neoplasms represent approximately 60% of surgical biopsies in ferrets with the majority being islet cell tumors, adrenal neoplasms, chordomas and skin tumors, all mentioned in the relevant sections above. There are others that are worth mentioning here. <u>Testicular neoplasms</u> are usually interstitial cell tumors and are often a combination of two or more neoplasms. The removal of cryptorchid testicles is very important in ferrets as at least one one neoplasm will always be found on a retained testicle. <u>Ovarian neoplasms</u> are tumors of germ cells or stromal cells. The second most commonly seen neoplasms are <u>Gastrointestinal neoplasms</u>. These are usually tumors of smooth muscle origin. Low-grade leiomyosarcommas are most commonly seen although mesotheliomas are sometimes seen in the peritoneum and serosal surfaces of ferrets. These mesotheliomas are locally aggressive and will result in marked abdominal effusion and often have a poor prognosis. <u>Pancreatic exocrine adenocarcinomas</u> are also found and these are also locally aggressive neoplasms. Within the musculoskeletal system, <u>Osteomas</u> have also been reported, arising from flat bones. These are expansile neoplasms composed of trabecular, well-differentiated bone and lined by osteoblasts. <u>Apocrine cysts</u> are also a common finding within the integumentary system of ferrets. These most commonly occur around the head, neck, prepuce and vulva due to the large number of scent glands in these areas. Apocrine gland carcinomas are also not uncommon and have a similar distribution. Apocrine carcinomas are locally aggressive neoplasms with a moderate potential for metastasis.