Viral diseases of ferrets

Ferret Gastroenterology

Ferrets (Mustela putorius furo) commonly present with gastrointestinal disease, which can be of noninfectious and infectious origin. Clinical signs are often nonspecific, and can include lethargy, anorexia, vomiting, diarrhea, and melena. Obtaining a detailed history, followed by a thorough physical examination and systematic diagnostic approach are the key to obtaining a correct diagnosis. This review provides an overview of ferret gastrointestinal anatomy and physiology, and diagnostic approach to gastrointestinal problems in ferrets, followed by relevant gastrointestinal diseases related to the different sections of the gastrointestinal tract, including their work up and treatment.

Induction and antiviral activity of ferret myxovirus resistance (Mx) protein 1 against influenza A viruses

Myxovirus resistance (Mx) proteins are products of interferon stimulated genes (ISGs) and Mx proteins of different species have been reported to mediate antiviral activity against a number of viruses, including influenza A viruses (IAV). Ferrets are widely considered to represent the 'gold standard' small animal model for studying pathogenesis and immunity to human IAV infections, however little is known regarding the antiviral activity of ferret Mx proteins. Herein, we report induction of ferret (f)Mx1/2 in a ferret lung cell line and in airway tissues from IAV-infected ferrets, noting that fMx1 was induced to higher levels that fMx2 both in vitro and in vivo. Overexpression confirmed cytoplasmic expression of fMx1 as well as its ability to inhibit infection and replication of IAV, noting that this antiviral effect of fMx1was modest when compared to cells overexpressing either human MxA or mouse Mx1. Together, these studies provide the first insights regarding the role of fMx1 in cell innate antiviral immunity to influenza viruses. Understanding similarities and differences in the antiviral activities of human and ferret ISGs provides critical context for evaluating results when studying human IAV infections in the ferret model.

Does Aleutian Disease Occur among Domestic Ferrets in Poland? Results of Preliminary Studies Conducted in Two Regions of Poland

Although ferrets are becoming increasingly popular as companion animals, their population in households is still far lower compared to cats or dogs. This results in a much smaller number of ferret specialists, and thus poorer diagnosis of various diseases, including the Aleutian disease. Aleutian disease is a slowly progressing viral disease which can cause different symptoms in these animals. The virus can also cause symptoms in different species of animals, but in the case of ferrets, there is relatively less information on about both the prevalence and symptoms of this disease. Therefore, the aim of this study was to determine the presence of antibodies and the virus itself in ferrets from two regions of Poland. Blood samples and rectal swabs were obtained from 61 domestic ferrets from Mazowieckie and Dolnośląskie voivodships. The presence of antibodies was determined using serological methods and real-time PCR analysis was performed to determine presence of viral DNA. Serological analyses demonstrated that 49% (n = 30) of the ferrets had antibodies against Aleutian disease virus (ADV). No relationship was observed between the prevalence of antibodies and age, sex, habitual residence or origin of ferrets. The real-time PCR did not confirm DNA of the ADV in any of the blood and rectal swab samples. Obtained results suggest that ADV circulates in the analyzed population of ferrets, therefore further studies in this direction should be carried out.

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.

Research Relevant Background Lesions and Conditions: Ferrets, Dogs, Swine, Sheep, and Goats

Animal models provide a valuable tool and resource for biomedical researchers as they investigate biological processes, disease pathogenesis, novel therapies, and toxicologic studies. Interpretation of animal model data requires knowledge not only of the processes/diseases being studied but also awareness of spontaneous conditions and background lesions in the model that can influence or even confound the study results. Species, breed/stock, sex, age, anatomy, physiology, diseases (noninfectious and infectious), and neoplastic processes are model features that can impact the results as well as study interpretation. Here, we review these features in several common laboratory animal species, including ferret, dog (beagle), pig, sheep, and goats.

Musculoskeletal and Neurologic Diseases

Ferrets may exhibit neurologic signs as a result of various conditions that may be of nervous or muscular origin. Neurologic examination follows the same principles as in small animal medicine. One of the main defect that may be screened during clinical examination is deafness. Congenital deafness in ferrets is associated with coat color patterns such as white markings and premature graying.In this species, paresis is a common presentation and may reflect a generalized weakness. Spinal disorder, intervertebral disk disease, and neoplasia are among the differential diagnosis. Diagnostic exams usually include advance diagnostic imaging such as CT-scan associated with myelography. Seizure is usually associated with hypoglycemia and insulinoma, but other causes such as hypocalcemia or intracranial disorders have been described. Ferrets are sensitive to various neurotropic infectious disease such as rabies, distemper, aleutian disease, or systemic coronavirus. Finally, muscular disorder such as disseminated idiopathic myofasciitis and myasthenia gravis have been recently described, and potential treatments have been intended.

Analysis of the efficacy of an adjuvant-based inactivated pandemic H5N1 influenza virus vaccine

This paper describes a preclinical study analyzing the immunogenicity and protective efficacy of Kazfluvac^®, an adjuvant-based inactivated pandemic influenza A/H5N1 virus vaccine. In this study, laboratory animals (ferrets and mice) were vaccinated by the intramuscular or intraperitoneal route at an interval of 14 days with two doses of the vaccine containing different concentrations of influenza virus hemagglutinin (HA) protein. HA protein without adjuvant (aluminum hydroxide and Merthiolate) was used as a control. As a negative control, we utilized PBS. We assessed the protective efficacy of the candidate vaccine by analyzing the response to challenge with the influenza virus strain A/chicken/Astana/6/05 (H5N1). Our experimental results revealed substantially reduced clinical disease and an increased antibody response, as determined by hemagglutination-inhibition (HAI) test and microneutralization assay (MNA). This study showed that the candidate vaccine is safe and elicits an antigen-dose-dependent serum antibody response. In summary, we determined the optimum antigen dose in a Kazfluvac^® adjuvant formulation required for induction of heightened immunogenicity and protective efficacy to mitigate H5N1 disease in experimental animals, suggesting its readiness for clinical studies in humans.

Ocular Examination and Corneal Surface Disease in the Ferret

This article provides a brief, clinically relevant review of corneal surface disease in the ferret. A description of the ophthalmic examination of the ferret is provided. Stepwise descriptions of the most common ophthalmic abnormalities are provided, along with common rule-outs.

Vaccination of Ferrets for Rabies and Distemper

Companion ferrets need to be vaccinated against 2 viral diseases that cause neurologic illness: canine distemper and rabies. Although not common in ferrets, both viruses are fatal in ferrets and rabies virus is also fatal in humans. In this article, we provide a basic review of the 2 diseases, highlighting key neurologic concerns. We also review and update current vaccine concerns from a practitioner's perspective, including available vaccines, vaccine schedule recommendations, vaccine reactions, and risk assessment. Last, we mention the ferret and its use in cutting-edge vaccine development.

Development of a duplex real-time RT-qPCR assay to monitor genome replication, gene expression and gene insert stability during in vivo replication of a prototype live attenuated canine distemper virus vector encoding SIV gag

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The duplex assay monitored replication, tissue distribution, and mRNA expression.

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The duplex assay monitored insert genetic stability during in vivo replication.

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Primary site of CDV replication in ferrets was abdominal cavity lymphoid tissue.

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CDV gRNA or mRNA was undetectable in brain tissue.

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Specific primers were used in the RT step to distinguish gRNA from mRNA.

Advancement of new vaccines based on live viral vectors requires sensitive assays to analyze in vivo replication, gene expression and genetic stability. In this study, attenuated canine distemper virus (CDV) was used as a vaccine delivery vector and duplex 2-step quantitative real-time RT-PCR (RT-qPCR) assays specific for genomic RNA (gRNA) or mRNA have been developed that concurrently quantify coding sequences for the CDV nucleocapsid protein (N) and a foreign vaccine antigen (SIV Gag). These amplicons, which had detection limits of about 10 copies per PCR reaction, were used to show that abdominal cavity lymphoid tissues were a primary site of CDV vector replication in infected ferrets, and importantly, CDV gRNA or mRNA was undetectable in brain tissue. In addition, the gRNA duplex assay was adapted for monitoring foreign gene insert genetic stability during in vivo replication by analyzing the ratio of CDV N and SIV gag genomic RNA copies over the course of vector infection. This measurement was found to be a sensitive probe for assessing the in vivo genetic stability of the foreign gene insert.

Mycoplasmosis in ferrets

A newly recognized respiratory disease of domestic ferrets is associated with a novel Mycoplasma species.

We report an outbreak of severe respiratory disease associated with a novel Mycoplasma species in ferrets. During 2009–2012, a respiratory disease characterized by nonproductive coughing affected ≈8,000 ferrets, 6–8 weeks of age, which had been imported from a breeding facility in Canada. Almost 95% became ill, but almost none died. Treatments temporarily decreased all clinical signs except cough. Postmortem examinations of euthanized ferrets revealed bronchointerstitial pneumonia with prominent hyperplasia of bronchiole-associated lymphoid tissue. Immunohistochemical analysis with polyclonal antibody against Mycoplasma bovis demonstrated intense staining along the bronchiolar brush border. Bronchoalveolar lavage samples from 12 affected ferrets yielded fast-growing, glucose-fermenting mycoplasmas. Nucleic acid sequence analysis of PCR-derived amplicons from portions of the 16S rDNA and RNA polymerase B genes failed to identify the mycoplasmas but showed that they were most similar to M. molare and M. lagogenitalium. These findings indicate a causal association between the novel Mycoplasma species and the newly recognized pulmonary disease.

A single amino acid in the HA of pH1N1 2009 influenza virus affects cell tropism in human airway epithelium, but not transmission in ferrets

The first pandemic of the 21^st century, pandemic H1N1 2009 (pH1N1 2009), emerged from a swine-origin source. Although human infections with swine-origin influenza have been reported previously, none went on to cause a pandemic or indeed any sustained human transmission. In previous pandemics, specific residues in the receptor binding site of the haemagglutinin (HA) protein of influenza have been associated with the ability of the virus to transmit between humans. In the present study we investigated the effect of residue 227 in HA on cell tropism and transmission of pH1N1 2009. In pH1N1 2009 and recent seasonal H1N1 viruses this residue is glutamic acid, whereas in swine influenza it is alanine. Using human airway epithelium, we show a differential cell tropism of pH1N1 2009 compared to pH1N1 2009 E227A and swine influenza suggesting this residue may alter the sialic acid conformer binding preference of the HA. Furthermore, both pH1N1 2009 E227A and swine influenza multi-cycle viral growth was found to be attenuated in comparison to pH1N1 2009 in human airway epithelium. However this altered tropism and viral growth in human airway epithelium did not abrogate respiratory droplet transmission of pH1N1 2009 E227A in ferrets. Thus, acquisition of E at residue 227 was not solely responsible for the ability of pH1N1 2009 to transmit between humans.

Naturally occurring influenza infection in a ferret (Mustela putorius furo) colony

Tissue samples from 2 juvenile ferrets (Mustela putorius furo) from a colony that was undergoing an outbreak of respiratory disease were submitted to the Iowa State University Veterinary Diagnostic Laboratory. Microscopic examination of lung samples revealed bronchointerstitial pneumonia with necrotizing bronchiolitis. Influenza A virus was detected in sections of formalin-fixed lung by immunohistochemistry and reverse transcription polymerase chain reaction assay. A field investigation of the premises and analysis of additional samples led to the confirmation and characterization of an influenza virus with high homology to contemporary reassortant H1N1 swine influenza viruses. Although ferrets have been used extensively to research the virulence and transmissibility of avian, human, and swine influenza virus strains, no published information exists on naturally occurring outbreaks of swine influenza in ferrets.

Clinical neurology of ferrets

Neurology represents an important specialty within ferret clinical medicine. Veterinarians should become familiar with the unique anatomic and physiologic differences between ferrets to improve their management of theses cases. In addition, veterinarians should use available diagnostic tests to confirm the presence of neurologic diseases. Recent advances in ferret medicine and veterinary neurology offer new capabilities to investigate and treat neurological disease in ferrets.

Exotic mammal renal disease: diagnosis and treatment

Knowledge of the renal anatomy and clinical pathology associated with renal disease can help the practitioner with interpretation of imaging procedures and urine, blood, and serum biochemical values. This article discusses specimen collection techniques, along with species variables in several clinical pathology parameters. Diagnostic tools and interpretations are discussed for the more common renal maladies affecting exotic mammals. Treatment guidelines are offered for general as well as specific exotic mammal renal diseases.