Mycobacterial infection in the ferret

Mycobacteriosis in a Pet Ferret (Mustela putorius furo) Caused by Mycobacterium xenopi: A Case Report on Neglected Risk of Zoonotic Transmission

Ferrets are highly susceptible to a wide range of mycobacteria, mainly M. bovis, M. avium, and M. triplex. Therefore, ferrets pose a risk of transmission of mycobacteriosis, especially zoonotically relevant tuberculosis. The aim of this study was to describe the findings of M. xenopi mycobacteriosis in a pet ferret and emphasize its zoonotic potential. A pet ferret had a history of weight loss, apathy, hyporexia, and hair loss. Abdominal ultrasound revealed splenomegaly with two solid masses and cystic lesions of the liver. Fine-needle aspiration cytology revealed numerous acid-fast bacilli in epithelioid cells, thus leading to the suspicion of mycobacterial infection. Because of its poor general condition, the ferret was euthanized. Necropsy examination revealed generalized granulomatous lymphadenitis, pneumonia, myocarditis, splenitis, and hepatitis. Histologically, in all organs, there were multifocal to coalescing areas of inflammatory infiltration composed of epithelioid macrophages, a low number of lymphocytes, and plasma cells, without necrosis nor multinucleated giant cells. Ziehl-Neelsen staining detected the presence of numerous (multibacillary) acid-fast bacteria, which were PCR-typed as M. xenopi. This is the first study showing the antimicrobial susceptibility testing of M. xenopi in veterinary medicine, describing the resistance to doxycycline. Overall, our results could facilitate further diagnosis and provide guidelines for the treatment protocols for such infections.

Ferrets as a model for tuberculosis transmission

Even with the COVID-19 pandemic, tuberculosis remains a leading cause of human death due to a single infectious agent. Until successfully treated, infected individuals may continue to transmit Mycobacterium tuberculosis bacilli to contacts. As with other respiratory pathogens, such as SARS-CoV-2, modeling the process of person-to-person transmission will inform efforts to develop vaccines and therapies that specifically impede disease transmission. The ferret (Mustela furo), a relatively inexpensive, small animal has been successfully employed to model transmissibility, pathogenicity, and tropism of influenza and other respiratory disease agents. Ferrets can become naturally infected with Mycobacterium bovis and are closely related to badgers, well known in Great Britain and elsewhere as a natural transmission vehicle for bovine tuberculosis. Herein, we report results of a study demonstrating that within 7 weeks of intratracheal infection with a high dose (>5 x 10³ CFU) of M. tuberculosis bacilli, ferrets develop clinical signs and pathological features similar to acute disease reported in larger animals, and ferrets infected with very-high doses (>5 x 10⁴ CFU) develop severe signs within two to four weeks, with loss of body weight as high as 30%. Natural transmission of this pathogen was also examined. Acutely-infected ferrets transmitted M. tuberculosis bacilli to co-housed naïve sentinels; most of the sentinels tested positive for M. tuberculosis in nasal washes, while several developed variable disease symptomologies similar to those reported for humans exposed to an active tuberculosis patient in a closed setting. Transmission was more efficient when the transmitting animal had a well-established acute infection. The findings support further assessment of this model system for tuberculosis transmission including the testing of prevention measures and vaccine efficacy.

MALDI-TOF Mass Spectrometry as a Rapid Screening Alternative for Non-tuberculous Mycobacterial Species Identification in the Veterinary Laboratory

Non-tuberculous mycobacteria (NTM) are difficult to identify by biochemical and genetic methods due to their microbiological properties and complex taxonomy. The development of more efficient and rapid methods for species identification in the veterinary microbiological laboratory is, therefore, of great importance. Although MALDI-TOF Mass Spectrometry (MS) has become a promising tool for the identification of NTM species in human clinical practise, information regarding its performance on veterinary isolates is scarce. This study assesses the capacity of MALDI-TOF MS to identify NTM isolates (n = 75) obtained from different animal species. MALDI-TOF MS identified 76.0% (n = 57) and 4% (n = 3) of the isolates with high and low confidence, respectively, in agreement with the identification achieved by Sanger sequencing of housekeeping genes (16S rRNA, hsp65, and rpoB). Thirteen isolates (17.3%) were identified by Sanger sequencing to the complex level, indicating that these may belong to uncharacterised species. MALDI-TOF MS approximated low confidence identifications toward closely related mycobacterial groups, such as the M. avium or M. terrae complexes. Two isolates were misidentified due to a high similarity between species or due to the lack of spectra in the database. Our results suggest that MALDI-TOF MS can be used as an effective alternative for rapid screening of mycobacterial isolates in the veterinary laboratory and potentially for the detection of new NTM species. In turn, Sanger sequencing could be implemented as an additional method to improve identifications in species for which MALDI-TOF MS identification is limited or for further characterisation of NTM species.

Retrospective Review of Mycobacterial Conjunctivitis in Cockatiels (Nymphicus hollandicus)

The etiologic disease organism responsible for causing mycobacteriosis in avian species is an acid-fast gram-positive bacterium. This bacterium causes granulomatous disease in various internal organs, but in cockatiels (Nymphicus hollandicus) it has been commonly identified within the conjunctival tissues. Twenty-six cases of mycobacterial conjunctivitis in cockatiels were diagnosed through histopathologic assessment of diseased tissue samples, Fite acid-fast staining, and polymerase chain reaction in this retrospective study. Clinicians who saw these cases were contacted, and information was obtained regarding recommended treatment protocols prescribed for the patients, the Mycobacterium species identified, and case outcomes. All patients in this retrospective study had a biopsy performed on the affected conjunctival tissue, and because of the small size of the patients, this excisional biopsy removed the affected tissue in its entirety or significantly debulked the lesion. Of the 26 cases, 10 were lost to follow-up, 4 were euthanatized, 7 died, and 5 were alive at the time this information was submitted for publication.

Pathology of Diseases of Geriatric Exotic Mammals

The review covers select disease conditions most frequently described in aging rodents (rats, mice, hamsters, guinea pigs), rabbits, and ferrets. The conditions are categorized by general organ systems, infectious diseases, and neoplasms. Two data systems, the Veterinary Medical Teaching Hospital and Comparative Pathology Laboratory at the University of California, Davis and Zoo/Exotic Pathology Service, Citrus Heights, California were used in the determining disease conditions to describe.

Systemic tuberculosis by MYCOBACTERIUM BOVIS in a free-ranging MARSICAN brown bear (URSUS ARCTOS MARSICANUS): a Case report

Background

Mycobacterium bovis is known to have a wide host range and has been isolated from numerous free-ranging wildlife species, carnivores included. In bears, M. bovis has been previously reported only from a culture of pooled lymph nodes of a black bear (Ursus americanus) in the absence of lesions. The aims of this study were to describe gross and microscopic pathological findings of M. bovis tuberculosis in a deceased Marsican brown bear (Ursus arctos marsicanus).

Case presentation

In March 2014, an adult female Marsican brown bear was found in the Abruzzo, Lazio and Molise National Park (Italy) showing severe non-specific clinical signs. The animal died soon after its discovery and the carcass was submitted to post-mortem examination to identify the cause of death. The bear was diagnosed with a severe Mycobacterium bovis infection, with both pathological and microbiological aspects suggesting ongoing generalization. A presumptive diagnosis of mycobacterial infection was initially made based on gross findings. Histopathology showed the presence of acid-fast bacilli in all sampled tissues along with poorly organized granulomatous lesions. Slow-growing Mycobacterium sp. was isolated from multiple organs (intestine, mesenteric lymph nodes, liver, spleen, lung and kidneys). The PCR and sequencing algorithm identified the Mycobacterium sp. isolate as M. bovis. Spoligotyping demonstrated that the M. bovis isolate belonged to spoligotype SB0120.

Conclusions

This is the first report of lethal M. bovis tuberculosis infection in a free-ranging brown bear. This pathogen could have serious adverse effects in an endangered relic population such as the Marsican brown bear. Stricter application of health regulations in force, surveillance of M. bovis infections in wild ungulates and carnivore scavengers, along with dismissal of supplementary feeding points intended for cattle or wildlife, are warranted to control the presence of bovine tuberculosis in wild and domestic animals in protected areas.

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.

Case of mycobacteriosis in a pet ferret in Poland

A seven-year-old dead pet ferret (Mustela putorius furo) was brought to the National Veterinary Research Institute, Department of Microbiology, to have the disease diagnosed and cause of death determined. Significant loss of fur and various numerous skin lesions—such as nodules, bruises and small scabs— were found. A prominent subcutaneous cyst filled with semiliquid mass was observed on the right hindlimb, and the left eyelid was slightly swollen left eyelid with symptoms of conjunctivitis. On the basis of combined findings, the authors concluded that the ferret’s death was caused by a generalized Mycobacterium aviumsubspecies avium infection. Some immunodeficiency resulting from ferret’s age could be a predisposing factor. A feral cat, which was the only animal the ferret had contacted several weeks before the appearance of the first clinical symptoms, was a possible source of infection.

Functional details of the Mycobacterium tuberculosis VapBC26 toxin-antitoxin system based on a structural study: insights into unique binding and antibiotic peptides

Toxin-antitoxin (TA) systems are essential for bacterial persistence under stressful conditions. In particular, Mycobacterium tuberculosis express VapBC TA genes that encode the stable VapC toxin and the labile VapB antitoxin. Under normal conditions, these proteins interact to form a non-toxic TA complex, but the toxin is activated by release from the antitoxin in response to unfavorable conditions. Here, we present the crystal structure of the M. tuberculosis VapBC26 complex and show that the VapC26 toxin contains a pilus retraction protein (PilT) N-terminal (PIN) domain that is essential for ribonuclease activity and that, the VapB26 antitoxin folds into a ribbon-helix-helix DNA-binding motif at the N-terminus. The active site of VapC26 is sterically blocked by the flexible C-terminal region of VapB26. The C-terminal region of free VapB26 adopts an unfolded conformation but forms a helix upon binding to VapC26. The results of RNase activity assays show that Mg²⁺ and Mn²⁺ are essential for the ribonuclease activity of VapC26. As shown in the nuclear magnetic resonance spectra, several residues of VapB26 participate in the specific binding to the promoter region of the VapBC26 operon. In addition, toxin-mimicking peptides were designed that inhibit TA complex formation and thereby increase toxin activity, providing a novel approach to the development of new antibiotics.

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.

Radiographic and ultrasonographic findings of the spleen and abdominal lymph nodes in healthy domestic ferrets

Objective

To describe the radiographic and ultrasonographic characteristics of the spleen and abdominal lymph nodes in clinically healthy ferrets.

Materials and Methods

Fifty‐five clinically healthy ferrets were prospectively recruited for this cross‐sectional study. Three‐view whole body radiographs and abdominal ultrasonography were performed on awake (23 out of 55) or sedated (32 out of 55) ferrets. On radiographs splenic and abdominal lymph node visibility was assessed. Splenic thickness and echogenicity and lymph node length, thickness, echogenicity, number and presence of cyst‐like changes were recorded.

Results

The spleen was radiographically detectable in all ferrets. On ultrasound the spleen was hyperechoic to the liver (55 out of 55) and mildly hyperechoic (28 out of 55), isoechoic (15 out of 55) or mildly hypoechoic (12 out of 55) to the renal cortices. Mean splenic thickness was 11.80 ±0.34 mm. Lymph nodes were radiographically discernible in 28 out of 55 ferrets and included caudal mesenteric and sublumbar nodes. An average of 9 ±2 lymph nodes (mean± standard deviation; mode 10) were identified in each ferret using ultrasound. A single large jejunal lymph node was identified in all ferrets and had a mean thickness of 5.28 ± 1.66 mm. For other lymph nodes the mean thickness measurements plus one standard deviation were less than 4.4 mm (95% confidence interval: ≤ 3.72 mm).

Clinical Significance

The information provided in this study may act as a baseline for evaluation of the spleen and lymph nodes in ferrets.

Coronavirus Infection in Ferrets: Antigen Distribution and Inflammatory Response

Multisystemic granulomatous lesions are the most common finding in ferrets infected by ferret systemic coronavirus (FRSCV). To characterize the inflammatory response developed against this virus, lesions from 4 naturally infected ferrets were examined. Lesions were classified into the 4 known types of granulomas (granulomas without necrosis [G], granulomas with necrosis [G-N], granulomas with neutrophils [G-NL], and diffuse granulomatous inflammation [DG]). The cellular composition of the lesions was characterized on the basis of cellular morphology and immunohistochemistry using markers for T and B-lymphocytes, plasma cells, macrophages, and neutrophils. The extent and distribution of viral antigen expression was also assessed. In G lesions, macrophages were mainly located in the center of the granuloma, with a moderate number of T-lymphocytes scattered among the macrophages, plasma cells, and B-lymphocytes. G-N lesions exhibited a necrotic center surrounded by abundant macrophages, some T-lymphocytes, plasma cells, and a few B-lymphocytes. In G-NL lesions, there was a central area dominated by neutrophils with low numbers of macrophages, plasma cells, and lymphocytes. DG presented similar cell proportions, but distributed evenly throughout the lesions. FRSCV was expressed in G, G-NL, G-N, and DG, with decreasing numbers of immunoreactive cells. This study reveals the important role of macrophages in the inflammatory response of ferrets against the virus and the variable proportions of leukocytes among different types of lesions, indicating their variable age. The results also confirm the similarities of the disease in ferrets to feline infectious peritonitis.

Mycobacteriosis in a domestic ferret (Mustela putorius furo)

A 4-year-old spayed female ferret presented with a 2-month history of anorexia, vomiting and occasional diarrhea. Abdominal ultrasonography revealed thickening of the gastric wall and enlarged abdominal lymph nodes. Biopsy samples from the thickened gastric wall, enlarged abdominal lymph nodes and liver were taken during an exploratory laparotomy. Based on the histopathological examination, mycobacterium infection was diagnosed. The bacterial species could not be identified by additional diagnostic tests of feces, including fecal smear, culture and polymerase chain reaction (PCR). The ferret was treated with prednisolone and multiple antimicrobials, including rifampicin, azithromycin and enrofloxacin, but did not improve with treatment and died 220 days after the first presentation.

Imaging findings in 14 domestic ferrets (Mustela putorius furo) with lymphoma

Lymphoma is the most common malignant neoplasia in domestic ferrets, Mustela putorius furo. However, imaging findings in ferrets with lymphoma have primarily been described in single case reports. The purpose of this retrospective study was to describe imaging findings in a group of ferrets with confirmed lymphoma. Medical records were searched between 2002 and 2012. A total of 14 ferrets were included. Radiographs (n = 12), ultrasound (n = 14), computed tomography (CT; n = 1), and magnetic resonance imaging (MRI; n = 1) images were available for review. Median age at the time of diagnosis was 5.2 years (range 3.25–7.6 years). Clinical signs were predominantly nonspecific (8/14). The time between the first imaging study and lymphoma diagnosis was 1 day or less in most ferrets (12). Imaging lesions were predominantly detected in the abdomen, and most frequently included intra‐abdominal lymphadenopathy (12/14), splenomegaly (8/14), and peritoneal effusion (11/14). Lymphadenopathy and mass lesions were typically hypoechoic on ultrasound. Mild peritoneal effusion was the only detected abnormality in two ferrets. Mild pleural effusion was the most common thoracic abnormality (3/12). Expansile lytic lesions were present in the vertebrae of two ferrets with T3‐L3 myelopathy and the femur in a ferret with lameness. Hyperattenuating, enhancing masses with secondary spinal cord compression were associated with vertebral lysis in CT images of one ferret. The MRI study in one ferret with myelopathy was inconclusive. Findings indicated that imaging characteristics of lymphoma in ferrets are similar to those previously reported in dogs, cats, and humans.

Diagnosis of liver disease in domestic ferrets (Mustela putorius)

Liver disease in ferrets is often subclinical and underdiagnosed. Clinical pathology and diagnostic imaging are needed to guide clinicians but definite diagnosis is based on histopathologic lesions. Inflammatory digestive conditions can lead to ascending tract infection and hepatobiliary inflammation. Ferrets have a specific sensitivity to hepatic lipidosis. Incidence of hepatic neoplasia is high in ferrets. After a summary of anatomy and physiology of the ferret liver, hepatic diseases known in ferret species are reviewed with their subsequent diagnostic procedures.