Selected emerging diseases in ferrets

Managing Disease Outbreaks in Captive Herds of Exotic Companion Mammals

Management of epizootics of exotic companion mammal herds relies on careful observance of animals, proper management and husbandry, adequate nutrition, and stress reduction. Many diseases occur because of the stress of weaning so anticipating this and maximizing sanitation and ventilation, minimizing overcrowding and concurrent disease, and providing enough fiber for herbivores is prudent. Antimicrobial therapy must be carefully considered in the route of administration and the likely risk of enterotoxemia development. Separation of affected animals, rapid diagnostic testing, and implementation of treatment and supportive care minimizes losses during epizootics. Knowledge of potential zoonotic pathogens is important for veterinarians and staff.

Emerging Zoonotic Diseases in Ferrets

As veterinarians, we may be the first to diagnose emerging zoonotic diseases in ferrets and may be at increased risk of exposure. Pseudomonas luteola is a bacterial infection that causes respiratory disease, panniculitis, sialadenitis, and abscess formation. Hepatitis E virus can cause subclinical infection, acute hepatitis, and persistent infection. Since the 2013 article discussing the 2009 influenza pandemic affecting ferrets, there has been an additional case of suspected anthroponotic infection in a pet ferret and experimental infection with influenza viruses from humans, cats, and dogs.

Identification of the environmental source of infection for a domestic ferret with cryptococcosis

Cryptococcosis, caused by the Cryptococcus gattii and C. neoformans species complexes, is an environmentally acquired mycosis affecting a broad range of host species. Among 9 communally housed ferrets, a 5-y-old castrated male ferret domiciled in an outdoor enclosure in Sydney, Australia was diagnosed with sinonasal cryptococcosis. Clinical signs resolved during 18 mo of itraconazole therapy, but the ferret was eventually euthanized because of splenic hemangiosarcoma. At postmortem, microscopic foci of persistent cryptococcosis were detected. The diagnosis raised concerns that the owners and other ferrets were exposed to a common environmental source of infection, thus prompting an investigation. Soil samples, swabs of a hollow eucalypt log (used for behavioral enrichment), and nasal swabs from 8 asymptomatic ferrets were collected. Nasal exudate (obtained at diagnosis) and tissues (collected at postmortem) were available from the clinical case. Bird seed agar culture resulted in a heavy growth of Cryptococcus spp. from one environmental site (the log), one nasal swab, and nasal exudate and tissues from the clinical case. All other samples were culture-negative. Sub-cultured isolates from the log were a mixture of C. gattii molecular type VGI and C. neoformans molecular type VNI. Ferret isolates were a similar mixture of C. gattii VGI (all disease isolates) and C. neoformans VNI (nasal-colonizing isolate). Multilocus sequence typing further revealed the ferret isolates as identical to environmental isolates collected from the log, confirming the log as the source of clinical disease and nasal colonization. The log was removed to prevent further exposure to a high environmental load of Cryptococcus spp.

Characterisation of the French ferret population, husbandry, reported medical care and feeding habits

Ferrets have become a common companion animal. But no data are available on the French population of ferrets. The goal of the survey was to characterise this population, including demographic characteristics, husbandry, reported medical care and feeding habits. Complete data were available for 1205 pet ferrets in 709 households. Most ferrets (86·1 %) lived indoors, 1 % received only artificial lighting, and 47 % chewed their cage. For 60 % of the ferrets, body weight was higher in winter and lower in summer. Neutered ferrets (58·5 % of males and 62·9 % of females) appeared lighter than intact ferrets of comparable age. A majority (52·4 %) of ferrets received a mix of commercial foods and fresh foods, but 28·6 % were offered no commercial foods. Data were analysed using several multivariable logistic regression models including age, sex, castration, food type and artificial lighting developed for four clinical outcome (lethargy and/or insulinoma, dental problems, diarrhoea and/or bird-seed stools and alopecia). Predictors of four clinical outcomes (lethargy, dental disease, diarrhoea and alopecia) were examined using multivariable logistic regression, with age, sex, neuter status, food type and artificial lighting as the exposure variables. Aged ferrets were more likely to have lethargy, insulinoma, dental problems and alopecia. Ferrets with artificial lighting were more likely to show alopecia. Additionally, ferrets fed commercial food only or a mixed diet (both commercial food and fresh food) were more likely to have lethargy, insulinoma, dental problems, diarrhoea and/or bird-seed stools compared with ferrets fed fresh food only. We also found a significant association between neutering and alopecia. It is to our knowledge the first description of the French population of the ferret as a companion animal.

Endocrinopathy and Aging in Ferrets

Ferrets have become more popular as household pets and as animal models in biomedical research in the past 2 decades. The average life span of ferrets is about 5-11 years with onset of geriatric diseases between 3-4 years including endocrinopathies, neoplasia, gastrointestinal diseases, cardiomyopathy, splenomegaly, renal diseases, dental diseases, and cataract. Endocrinopathies are the most common noninfectious disease affecting middle-aged and older ferrets. Spontaneous neoplasms affecting the endocrine system of ferrets appear to be increasing in prevalence with a preponderance toward proliferative lesions in the adrenal cortex and pancreatic islet cells. Diet, gonadectomy, and genetics may predispose ferrets to an increased incidence of these endocrinopathies. These functional proliferative lesions cause hypersecretion of hormones that alter the physiology and metabolism of the affected ferrets resulting in a wide range of clinical manifestations. However, there is an apparent dearth of information available in the literature about the causal relationship between aging and neoplasia in ferrets. This review provides a comprehensive overview of the anatomy and physiology of endocrine organs, disease incidence, age at diagnosis, clinical signs, pathology, and molecular markers available for diagnosis of various endocrine disorders in ferrets.

Computed tomography and magnetic resonance for the advanced imaging of the normal nasal cavity and paranasal sinuses of the koala (Phascolarctos cinereus)

The objective of this study is to describe computed tomography (CT) and magnetic resonance (MR) for the cross-sectional imaging of the normal anatomy of the nasal cavity and paranasal sinuses of the koala (Phascolarctos cinereus), to provide reference figures for gross anatomy with corresponding CT and MR images and to compare the features of the nasal cavity and paranasal sinuses of the normal koala with that reported in other domestic species. Advanced imaging can be used to aid in diagnosis, to plan surgical intervention, and to monitor therapeutic responses to diseases of the nasal passages in koalas. One clinically normal koala was anesthetized twice for the separate acquisition of dorsal CT scan images and transverse, dorsal, and sagittal MR images of its nasal cavity and paranasal sinuses. Sagittal and transverse CT planes were reformatted. Three fresh koala skulls were also transected in one of each transverse, sagittal, and dorsal planes and photographed. The CT and MR images obtained were matched with corresponding gross anatomic images and the normal bone, tissues and airway passages were identified. All anatomic structures were readily identifiable on CT, magnetic resonance imaging (MRI), and gross images. CT and MRI are both valuable diagnostic tools for imaging the nasal cavities and paranasal sinuses of koalas. Images obtained from this project can be used as baseline references for future comparison with diseased koalas to help with diagnosis, surgical intervention, and response to therapy.

Biology and Diseases of Ferrets

Ferrets (Mustela putorius furo) belong to the ancient family Mustelidae, which is believed to date back to the Eocene period, some 40 million years ago. The taxonomic groups in the family Mustelidae, as recognized by Nowak (1999), include 67 species in 25 genera from North, Central, and South America; Eurasia; and Africa. No other carnivore shows such diversity of adaptation, being found in a wide variety of ecosystems ranging from arctic tundra to tropical rainforests. Mustelids have retained many primitive characteristics, which include relatively small size, short stocky legs, five toes per foot, elongated braincase, and short rostrum (Anderson, 1989). The Mustelinae is the central subfamily of the Mustelidae. The best-known members of the Mustelinae are the weasels, mink, ferrets (genus Mustela), and the martens (genus Martes) (Anderson, 1989). The genus Mustela is divided into five subgenera: Mustela (weasels), Lutreola (European mink), Vison (American mink), Putorius (ferrets), and Grammogale (South American weasels). The smallest member of the Mustelidae family is the least weasel (Mustela nivalis), which weighs as little as 25 g, and the largest member is the sea otter (Enhydra lutris), which can weigh as much as 45 kg (Nowak, 1999).

Ferrets as sentinels of the presence of pathogenic Cryptococcus species in the Mediterranean environment

Cryptococcus gattii is a pathogenic environmental yeast that is considered to be emerging in different areas of the world including the Mediterranean Basin. Exposure to infection might be more likely in animals than in human beings, given their closer relationship with the natural habitat of the yeast, vegetation and soil. Thus, animals, and especially pets, can act as indicators of the presence of this yeast in a determined area. Domestic ferrets (Mustela putorius furo) have become common pets in the past 10-20 years. Their natural behavior of sniffing around and going inside narrow spaces makes them prone to contact with decaying organic matter and soil, the substrate for Cryptococcus species. This study describes two cases of cryptococcosis in ferrets in the Iberian Peninsula and Balearic Islands and documents a relationship of ferret cryptococcosis with environmental isolates in the same locations. Here, we emphasize the importance of how an adequate identification and environmental search of the yeast leads to a better understanding of the epidemiology of cryptococcosis and suggests ferrets may act as sentinels for this fungal disease.

Quantifying insulin sensitivity and entero-insular responsiveness to hyper- and hypoglycemia in ferrets

Ferrets are an important emerging model of cystic fibrosis related diabetes. However, there is little documented experience in the use of advanced techniques to quantify aspects of diabetes pathophysiology in the ferret. Glycemic clamps are the gold standard technique to assess both insulin sensitivity and insulin secretion in humans and animal models of diabetes. We therefore sought to develop techniques for glycemic clamps in ferrets. To assess insulin sensitivity, we performed euglycemic hyperinsulinemic clamps in 5–6 week old ferrets in the anesthetized and conscious states. To assess insulin secretion, we performed hyperglycemic clamps in conscious ferrets. To evaluate responsiveness of ferret islet and entero-insular hormones to low glucose, a portion of the hyperglycemic clamps were followed by a hypoglycemic clamp. The euglycemic hyperinsulinemic clamps demonstrated insulin responsiveness in ferrets similar to that previously observed in humans and rats. The anesthetic isoflurane induced marked insulin resistance, whereas lipid emulsion induced mild insulin resistance. In conscious ferrets, glucose appearance was largely suppressed at 4 mU/kg/min insulin infusion, whereas glucose disposal was progressively increased at 4 and 20 mU/kg/min insulin. Hyperglycemic clamp induced first phase insulin secretion. Hypoglycemia induced a rapid diminishment of insulin, as well as a rise in glucagon and pancreatic polypeptide levels. The incretins GLP-1 and GIP were affected minimally by hyperglycemic and hypoglycemic clamp. These techniques will prove useful in better defining the pathophysiology in ferrets with cystic fibrosis related diabetes.