Evaluation of a Novel Battery-Operated Tumbler Device for Use in the Detection of Mouse Pathogens for Rodent Health Monitoring.

The search for alternatives to live animal sentinels in rodent health monitoring programs is fundamental to the 3Rs (Reduction, Replacement, and Refinement) of animal research. We evaluated the efficacy of a novel battery-operated tumbler device that rotates soiled bedding in direct contact with sample media against the use of exhaust sample media and soiled bedding sentinel (SBS) mice. Four rodent racks were used, each with 3 test cages: a cage with a tumbler device that rotated for 10min twice a week (TUM10), a cage with a tumbler device that rotated for 60min twice a week (TUM60), and a cage housing 2 female Crl:CD1(ICR) mice. Every 2 wk, each test cage received soiled bedding collected from all cages on each respective rack. In addition to soiled bedding, the tumbler device contained various sample collection media: a contact Reemay filter (3mo-cRF) that remained in the tumbler for the duration of the study, a contact Reemay filter (1mo-cRF) that was replaced monthly, adhesive swabs (AS) that were added at every biweekly cage change, and an exhaust Reemay filter located at the exhaust outlet of the cage. All analyses were performed by direct PCR for both sample media in the animal-free methods, and fecal pellet, body swab, and oral swabs were collected from sentinel mice. Out of 16 total pathogens detected, assessment of 1mo-Crf from both TUM10 and TUM60 cages detected 84% and 79% of pathogens, respectively, while SBS samples detected only 47% of pathogens. AS in TUM60 and TUM10 cages detected the fewest pathogens (24% and 13%, respectively). These results indicate that the novel tumbler device is an effective and reliable tool for rodent health monitoring programs and a suitable replacement for live animal sentinels. In this study, 1mo-cRF in TUM10 cages detected the highest number of pathogens.

Tissue cysts and serological detection toxoplasmosis among wild rats from Surabaya, East Java, Indonesia.

Background: The protozoan Toxoplasma gondii is the source of zoonosis toxoplasmosis and causes public health problems throughout the world. Environmental contamination by oocysts excreted by cats as definitive hosts affects the spread of this disease. Wild rats as rodents can be used as an indicator of environmental contamination by oocysts, considering that rats have a habit of living in dirty environments and can be infected by oocysts from the environment. Aim: This study aims to detect toxoplasmosis from tissue cysts and serological tests in wild rats as an indicator of environmental contamination in Surabaya. Methods: A total of 100 wild rats collected from Surabaya were collected in five areas (West, East, Central, North, and South of Surabaya) obtained from three trapping locations: housing, dense settlements, and markets. All samples were examined microscopically for parasitological tests through the brain tissue samples, and the serum was examined using the toxoplasma modified agglutination test to detect the presence of IgG and Immunoglobulin M (IgM). Results: This research used 100 wild rat samples, 77 Rattus tanezumi and 33 Rattus norvegicus, with evidence of 31% in serology and active infection with 19% tissue cyst. The results showed that the seroprevalence of T. gondii in wild rats was 31% (30% for IgG and 1% for IgM). Tissue cysts in the rat brain samples tested were 19% (19/100). The IgG prevalence rate in female rats was 25% (8/32), while for males, it was 32.3% (22/68). The highest seropositive IgG from densely populated settlements was 50%, markets were 25.8%, and housing was 12.1%. The highest seropositive IgM from densely populated settlements was 2.8%. Population density and the presence of cats are factors supporting the high seropositive rate at the trapping location. Conclusion: This study revealed that there has been toxoplasmosis contamination in Surabaya with evidence of 31% in serology and active infection with 19% tissue cyst. It is necessary for controlling with surveillance in cats to prevent transmission in humans.

Assessing Methods for Replacement of Soiled Bedding Sentinels in Cage-level Exhaust IVC Racks.

Soiled bedding sentinel programs have long been the cornerstone of rodent health monitoring surveillance. Many recent studies have evaluated methods to replace live animals in these programs; however, the type of ventilated rack being used greatly influences the detection rate of adventitious pathogens. This study evaluated 4 alternative sampling techniques across 5 distinct vivaria and assessed their accuracy in detecting 5 pathogens. Testing was done in an operational (real-world) setting using IVC racks that vent air at the cage level. The 5 agents surveyed were mouse norovirus, Helicobacter spp., Rodentibacter spp. Entamoeba muris, and Spironucleus muris. Samples were collected for subsequent PCR assays as follows: 1) cages with live sentinels exposed to soiled bedding; 2) filter paper placed on the lid of an unoccupied cage containing soiled bedding; 3) filter paper placed in the bedding of an unoccupied cage that contained soiled bedding; 4) swabs from an unoccupied sentinel cage that contained soiled bedding; and 5) pooled swabs from colony cages admixed with swabs from soiled bedding sentinel mice. Cumulative accuracy for all pathogens of interest was highest with the existing soiled bedding sentinel program, followed by pooled swabs of colony cages mixed with swabs from occupied soiled bedding sentinel cages. Soiled bedding sentinel cages detected mouse norovirus, Helicobacter spp., and S. muris with the highest accuracy; the pooled swabs were best in detecting Rodentibacter spp. and E. muris. The findings suggest that with the type of rack and caging used in our facilities, the soiled bedding sentinel method has highest concurrence with the expected health status of an animal room, and the results from this method can be enhanced with the addition of pooled swabs of colony animals.

Rodent Dermatology.

This article reviews the most common dermatologic conditions of the pet rodent population, including the prevalence, clinical signs, diagnosis, and treatment recommendations.

Spontaneous Pituitary Neoplasm in Two Female Geriatric Southern Giant Pouched Rats (Cricetomys ansorgei).

Southern giant pouched rats (Cricetomys ansorgei) are a small muroid species native to the sub-Saharan Africa. Their exceptionally developed olfactory system, trainability, and relatively small size makes them useful working animals for various applications in humanitarian work. At our institution, a breeding colony of Southern giant pouched rats is maintained to study their physiology and utility as scent detectors. This case report describes the occurrence of spontaneous pituitary neoplasms with distinct clinical presentations in 2 geriatric (approximately 7.5 y old) wild-caught female Southern giant pouched rats. The first pouched rat displayed vestibular deficits, including left-sided head tilt, ataxia, disorientation, and circling. MRI revealed a large, focal heterogeneous mass arising from the pituitary fossa. The second pouched rat presented with polyuria, polydipsia, and hyperglycemia but no neurologic signs. Examination after euthanasia revealed a prolactin (PRL)-expressing pituitary carcinoma and adenoma in the first and second pouched rat, respectively, associated with mammary hyperplasia in both animals. This is the first report of spontaneous PRL-producing pituitary tumors in Southern giant pouched rats.

Using Filter Media and Soiled Bedding in Disposable Individually Ventilated Cages as a Refinement to Specific Pathogen-free Mouse Health Monitoring Programs.

Molecular-based methods have shown potential for improving pathogen detection and reducing animal use. While increasing evidence supports rodent-free environmental health PCR pathogen detection, limited information is available regarding efficacy for disposable individually ventilated caging systems. In such systems, testing of plenum exhaust air dust is ineffective, and the use of collection media is optimal. We performed a series of studies to compare PCR infectious agent detection with dust collected on media placed in a mouse-free soiled bedding cage, the cage exhaust filter of an occupied sentinel cage, and direct sampling from colony and sentinel mice with traditional soiled bedding mouse sentinels. We hypothesized that after a 3-mo period, testing of filter media agitated in a soiled bedding cage would be equal to or more sensitive than more traditional methods. Agitated media detected Astrovirus-1, segmented filamentous bacteria and Helicobacter ganmani to a degree comparable to testing lid exhaust filter PCR from a sentinel mouse cage, but opportunists such as Staphylococcus aureus and Proteus mirabilis were not detected consistently, and H. hepaticus was not detected at all. Direct sampling of pooled fecal pellets and body swabs from sentinel mice and testing using PCR also failed to reliably detect opportunists and Helicobacter spp. While further work is needed to refine use of filter media in soiled bedding for detection of lower prevalence opportunists, this report provides evidence that a rodent-free method of reliably detecting murine agents in a disposable individually ventilated cage system with cage-level filtration outperforms direct sampling of soiled bedding sentinel mice.

Using Sterile Flocked Swabs as an Alternative Method for Rodent Health Monitoring.

Routine health monitoring is an integral part of managing SPF rodent colonies. In recent years, rack-level environmental sampling has been introduced as an adjunct method or replacement for exposure of sentinel rodents to soiled bedding. However, rack-level environmental monitoring is not compatible with rodent housing systems that have cage-level filtration. The current study investigated whether exposure of sterile flocked swabs to soiled bedding can be an alternative sampling method for routine health monitoring in mice, thus replacing the use of sentinels in soiled-bedding cages. Flocked swabs were placed in cages containing pooled samples of soiled bedding but no mice; swabs remained there for 90 d, with weekly agitation and biweekly swabbing of the cage floor to mimic the agitation of soiled bedding by sentinel mice and facilitate the collection of dust particles. Fecal samples were collected from both colony and sentinel mice. For environmental samples, exhaust debris was collected from the rack plenum, and dust samples were collected from the exhaust hose. All samples were collected on days 88 through 91 and were tested for multiple pathogens by using real-time PCR assays. To determine the diagnostic agreement of flocked swab sampling with the other methods, we used κ statistics to compare the test results from flocked swabs with those from sentinel feces, exhaust debris, and colony animal feces; we found excellent agreement between the colony feces and the flocked swab methods. The sterile flocked swab method detected all enzootic pathogens in the colonies tested. Results from flocked swab samples had the least agreement with sentinel feces, which also failed to detect the presence of fur mites. This study supports the use of sterile flocked swabs as alternative to using sentinel mice, thus conforming to the guiding principles of replacement and reduction in the use of animals for routine colony health monitoring.

Cardiology in Rodents, Rabbits, and Small Exotic Mammals-Diagnostic Workup.

The incidence of cardiac diseases in pet rabbits and rodents increased over the past decade as these species live longer and diagnostics methods are more precise to diagnose heart diseases even in small-sized animals. The article summarizes diagnostics of cardiac diseases in selected exotic companion mammals, particularly in rabbits, guinea pigs, chinchillas, and rats. The emphasis of the paper is given on clinical examination, thoracic radiography, electrocardiography, and echocardiography.

Detection and Transmission of Proteus mirabilis in Immunodeficient Mice.

The exclusion of opportunistic pathogens is important for protecting animal health and ensuring desired research outcomes in highly immunodeficient mice. Proteus mirabilis has been associated with gastrointestinal tract lesions, septicemia, pyelonephritis, splenomegaly, and hepatitis and can influence select mouse models. To inform health-surveillance practices after we experienced difficulty in excluding P. mirabilis from our mouse colony, we aimed to determine the likelihood of detecting P. mirabilis-positive immunocompromised (SRG), immunovague (Fbn1+/-), and immunocompetent (CD1) colony mice through culture and PCR testing; to evaluate transmission via 2 sentinel-based approaches (direct contact and indirect dirty-bedding transfer); and to further characterize associated pathology. We hypothesized that immunocompromised mice would be better detectors and transmitters of P. mirabilis. Multiple logistic regression models were used for analysis and included PCR copy number, repeated testing, age, sex, and antibiotic-treated (trimethoprim-sulfamethoxazole) diet as covariates. Repeated testing over 10 wk showed that P. mirabilis -colonized immunocompromised colony mice were 95 times more likely than immunocompetent mice to test positive by culture and 30 times more likely by PCR assay. Sentinel mice were 15 times more likely to test positive by PCR assay for P. mirabilis when exposed by direct contact compared with dirty bedding and 18 times more likely to test positive when exposed to positive immunocompromised as compared with immunocompetent colony mice. After 10 wk of exposure, 3.8% of dirty-bedding sentinel PCR tests were positive, as compared with 30.7% of contact sentinels. Only immunocompromised mice on antibiotic diet (37.5%) developed lesions of the urogenital tract and abdominal cavity consistent with known pathology of P. mirabilis. Our findings suggest that PCR testing of dirty-bedding sentinels alone is not sufficient for the detection of P. mirabilis in mouse colonies. Direct-contact sentinels and testing of colony mice-especially if immunocompromised-with adjunct culture may facilitate successful bioexclusion.

Retrospective analysis of risk factors, clinical features, and prognostic indicators for urolithiasis in guinea pigs: 158 cases (2009-2019).

OBJECTIVE: To investigate risk factors, clinical features, and prognostic indicators in guinea pigs with urolithiasis. ANIMALS: 158 guinea pigs with urolithiasis. PROCEDURES: Medical records of an exotics animal specialty service were searched, identifying guinea pigs with urolithiasis. Signalment, clinical data, and outcomes were recorded. Variables of interest were analyzed for statistical associations with outcome. RESULTS: Overall, 54.4% (86/158) of animals survived to discharge. Median survival time was 177 days. Females (53.2%; 84/158) were more common than males (46.8%; 74/158). Males were presented younger (mean age, 3.64 years) than females (4.41 years). In 81 of 154 (52.5%) cases, animals were presented with primary urinary concerns, while 73 (47.5%) presented for nonurinary primary concerns. Females more commonly presented with distal urinary tract urolithiasis (63/84; 75%) but fared better overall with a longer median survival time (1,149 days) than males (59 days). Surgical intervention was not a risk factor for nonsurvival; however, increased age (> 4.1 years), male sex, anorexia, weight loss, and lower rectal temperature (< 37.2 °C) on presentation were associated with nonsurvival. Reoccurrence was noted in 13.9% (22/158) of cases, at an average of 284 days. CLINICAL RELEVANCE: Urolithiasis should always be considered a differential diagnosis for any unwell guinea pig. In particular, distal urinary tract urolithiasis should be considered in females. A poorer prognosis was associated with older, male guinea pigs, and those displaying anorexia, weight loss, and hypothermia. The need for surgical intervention should not confer a poorer outcome. Further studies are needed to determine specific risk factors and identify possible preventative measures.

Why serology just is not enough: Strategic parvovirus risk assessment using a novel qPCR assay.

Health monitoring of laboratory rodents not only improves animal health but also enhances the validity of animal experiments. In particular, infections of laboratory animals with murine parvoviruses influence biomedical research data. Despite strict barrier housing, prevalence remains high in animal facilities, leading to increased risk of parvovirus introduction after the import of contaminated mice. Unfortunately, hygienic rederivation can be challenging, since gametes often contain residual virus material. Consequently, the process has to be closely monitored with highly sensitive diagnostic methods to verify parvovirus decontamination of the rederived progeny. However, diagnostic sensitivity of traditional methods is often low and requires testing of large animal cohorts. Therefore, we aimed to develop a powerful quantitative real-time polymerase chain reaction (qPCR) assay for the fast and reliable detection of murine parvoviruses in different sample materials. We validated the assay within an infection experiment and systematically analysed various animal-derived and environmental sample materials. We further developed a strategic risk assessment procedure for parvovirus monitoring after embryo transfer. Our novel qPCR assay reliably detected parvovirus DNA in a broad variety of sample materials, with environmental samples dominating in the acute phase of infection, whereas animal-derived samples were more suitable to detect low virus loads in the chronic phase. Here, the assay served as a highly sensitive screening method for parvovirus contamination in mouse colonies, requiring significantly lower sample sizes than traditional methods like conventional PCR and serology. Thus, the use of our novel qPCR assay substantially improves parvovirus diagnostics, enhancing research validity according to the 6Rs.

Assessing rodents as carriers of pathogenic Leptospira species in the U.S. Virgin Islands and their risk to animal and public health.

Leptospirosis is a global zoonotic disease caused by pathogenic bacteria of the genus Leptospira. We sought to determine if rodents in U.S. Virgin Islands (USVI) are carriers of Leptospira. In total, 140 rodents were sampled, including 112 Mus musculus and 28 Rattus rattus. A positive carrier status was identified for 64/140 (45.7%); 49 (35.0%) were positive by dark-field microscopy, 60 (42.9%) by culture, 63 (45.0%) by fluorescent antibody testing, and 61 (43.6%) by real-time polymerase chain reaction (rtPCR). Molecular typing indicated that 48 isolates were L. borgpetersenii and 3 were L. kirschneri; the remaining nine comprised mixed species. In the single culture-negative sample that was rtPCR positive, genotyping directly from the kidney identified L. interrogans. Serotyping of L. borgpetersenii isolates identified serogroup Ballum and L. kirschneri isolates as serogroup Icterohaemorrhagiae. These results demonstrate that rodents are significant Leptospira carriers and adds to understanding the ecoepidemiology of leptospirosis in USVI.

Zoonotic pathogen screening of striped field mice (Apodemus agrarius) from Austria.

The striped field mouse (Apodemus agrarius) is known to carry several zoonotic pathogens, including Leptospira spp. and Dobrava-Belgrade orthohantavirus (DOBV). Since its first detection in 1996 in south-east Austria, the striped field mouse has further expanded its range in Austria. Here, we screened 35 striped field mice collected in an Austrian region near the Hungarian border for DOBV, Leptospira spp. and seven vector-borne pathogens. Hantavirus RT-PCR screening and DOBV IgG ELISA analysis led to the detection of two DOBV-positive striped field mice. The complete coding sequences of all three genome segments of both strains were determined by a combination of target enrichment and next-generation sequencing. Both complete coding S segment sequences clustered within the DOBV genotype Kurkino clade with the highest similarity to a sequence from Hungary. In one of 35 striped field mice, Leptospira borgpetersenii sequence type (ST) 146 was detected. Bartonella spp., Borrelia miyamotoi and Neoehrlichia mikurensis DNA was detected in four, one and two of 32 mice, respectively. Babesia, Anaplasma, Ehrlichia and Rickettsia specific DNA was not detected. Future investigations will have to determine the prevalence and invasion of these pathogens with the ongoing range expansion of the striped field mouse in Austria.

DIAGNOSING AND CATEGORIZING LEPROSY IN LIVE EURASIAN RED SQUIRRELS (SCIURUS VULGARIS) FOR MANAGEMENT, SURVEILLANCE, AND TRANSLOCATION PURPOSES.

The presence of Mycobacterium lepromatosis and Mycobacterium leprae in Eurasian red squirrel (Sciurus vulgaris, ERS) carcasses throughout the British Isles, and leprosy as a disease, have recently been reported using histological and molecular diagnostic methods. In 2016, the first longitudinal study of ERS affected by leprosy was initiated. One of the main challenges was the reliable diagnosis of leprosy in live ERS, which is important for (a) welfare and case management and (b) surveillance or pretranslocation screening efforts. We explored diagnostic methods ranging from detailed clinical assessment and informative categorization of observed lesions, thermal imaging, serology (antiphenolic glycolipid-I antibody [αPGL-I] detection) to molecular methods (polymerase chain reaction [PCR]). For PCR the ear was established as the optimal sampling site. Based on the experiences from this 2-yr study we propose an objective categorization system for clinical lesions and a diagnostic framework for the combination of the diagnostic tools we found to be effective in live ERS: clinical assessment, αPGL-I serology, and PCR. Thermal imaging did not offer additional information for leprosy diagnostics in ERS. We propose an amended definition of leprosy lesions in ERS as "skin areas of local hair loss, in which a firm-rubbery, glossy swelling develops, that may ulcerate" and standardized terminology for describing ERS leprosy status. The information presented forms the basis of a consistent, reliable diagnostic and reporting system for leprosy cases in ERS.

Severe pneumonia in a street rat (Rattus norvegicus) caused by Rodentibacter rarus strain RMC2.

Background: Rodents are one of the most dangerous reservoirs and carriers of infectious diseases. Gradually, rats have become predominant in cities, sometimes staying in close vicinity to humans, pets, and other animals. Consequently, they tend to increase the transmission risk of pathogens. Case Description: Here, we report an original case of bacterial pneumonia in a street rat (Rattus norvegicus). The rat was found dead on a street in the chief town of Marseille (France) after being run over by a car. The necropsy of the corpse revealed generalized granulomatous pneumonia in almost all the pulmonary lobes. Lung lesions and predominantly multiple fibro-inflammatory areas are presumably the witness of an infectious etiology. Bacterial isolation was carried out from lung tissues. Colonies were identified by MALDI-TOF MS and confirmed by 16S rRNA sequencing. The following bacteria were identified: Staphylococcus cohnii, Bordetella bronchiseptica, Bordetella parapertussi, Corynebacterium glucuronolyticum, Pelistega suis and Rodentibacter rarus. Based on the histopathological diagnosis and the avoidance approach, the most likely etiological agent of pneumonia is therefore R. rarus, a little-known Pasteurellales bacterium that is closely related to Rodentibacter pneumotropicus. Conclusion: These data emphasize the severity of R. rarus infection in rodents. Thus, pointing out a potential risk for other animals (dogs, cats, and birds), as well as humans. The health monitoring program for rodents and rabbits pasteurellosis should now include R. rarus. Therefore, the pathological effect of the Rodentibacterspecies and/or strains needs to be better explored.

Respiratory Diseases in Guinea Pigs, Chinchillas and Degus.

The diagnosis and treatment of respiratory disease in pet guinea pigs, chinchillas, and degus still face profoundly serious challenges owing to their relatively small size, conspicuous clinical signs, difficulty for sampling, and insufficient scientific evidence to correlate signs and particular pathologies. This article is intended to summarize the available information on the relevant anatomy, physiology, and respiratory pathology in these species.

Simultaneous serodetection of major rat infectious pathogens by a multiplex immunochromatographic assay.

Rapid and simple serologic tests that require only a small amount of blood without the euthanization of animals are valuable for microbial control in colonies of laboratory animals. In this study, we developed a multiplex immunochromatographic assay (ICA) for detection of antibodies to Sendai virus (also known as hemagglutinating virus of Japan), hantavirus, and sialodacryoadenitis virus, which are causative agents of major infectious diseases in rats. For this assay, an ICA strip was placed into a microtube containing 150 µl PBS and either 0.75 µl of rat serum or 1.5 µl of whole blood. Binding antibodies were visualized by using anti-rat IgG antibody-conjugated colloidal gold. Under these conditions, the multiplex ICA simultaneously and specifically detected antibodies to multiple antigens. Positive serum samples for each infectious disease were used to evaluate the sensitivity and specificity of the multiplex ICA. The sensitivities of the multiplex ICA for Sendai virus, hantavirus, and sialodacryoadenitis virus were 100%, 100%, and 81%, respectively. No nonspecific reactions were observed in any of the 52 positive sera against heterologous antigens. In addition, 10 samples of uninfected sera did not show any bands except for the control line. These observations indicate high specificity of the multiplex ICA. Moreover, the multiplex ICA could be applied to diluted blood. These results indicate that the multiplex ICA is appropriate for rapid and simple serological testing of laboratory rats.