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Abstract
Environmental complexity is an experimental paradigm as well as a potential part of animals' everyday housing experiences. In experimental uses, researchers add complexity to stimulate brain development, delay degenerative brain changes, elicit more naturalistic behaviors, and test learning and memory. Complexity can exacerbate or mitigate behavioral problems, give animals a sense of control, and allow for expression of highly driven, species-typical behaviors that can improve animal welfare. Complex environments should be designed thoughtfully with the animal's natural behaviors in mind, reported faithfully in the literature, and evaluated carefully for unexpected effects.
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Affiliation(s)
- Kathleen R Pritchett-Corning
- Office of Animal Resources, Faculty of Arts and Sciences, Harvard University, Cambridge, Massachusetts.,Department of Comparative Medicine, University of Washington, Seattle, Washington
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2
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Theil JH, Ahloy-Dallaire J, Weber EM, Gaskill BN, Pritchett-Corning KR, Felt SA, Garner JP. The epidemiology of fighting in group-housed laboratory mice. Sci Rep 2020; 10:16649. [PMID: 33024186 PMCID: PMC7538892 DOI: 10.1038/s41598-020-73620-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 09/15/2020] [Indexed: 12/14/2022] Open
Abstract
Injurious home-cage aggression (fighting) in mice affects both animal welfare and scientific validity. It is arguably the most common potentially preventable morbidity in mouse facilities. Existing literature on mouse aggression almost exclusively examines territorial aggression induced by introducing a stimulus mouse into the home-cage of a singly housed mouse (i.e. the resident/intruder test). However, fighting occurring in mice living together in long-term groups under standard laboratory housing conditions has barely been studied. We performed a point-prevalence epidemiological survey of fighting at a research institution with an approximate 60,000 cage census. A subset of cages was sampled over the course of a year and factors potentially influencing home-cage fighting were recorded. Fighting was almost exclusively seen in group-housed male mice. Approximately 14% of group-housed male cages were observed with fighting animals in brief behavioral observations, but only 14% of those cages with fighting had skin injuries observable from cage-side. Thus simple cage-side checks may be missing the majority of fighting mice. Housing system (the combination of cage ventilation and bedding type), genetic background, time of year, cage location on the rack, and rack orientation in the room were significant risk factors predicting fighting. Of these predictors, only bedding type is easily manipulated to mitigate fighting. Cage ventilation and rack orientation often cannot be changed in modern vivaria, as they are baked in by cookie-cutter architectural approaches to facility design. This study emphasizes the need to invest in assessing the welfare costs of new housing and husbandry systems before implementing them.
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Affiliation(s)
- Jacob H Theil
- Campus Veterinary Services, University of California, Davis, One Shields Ave., Davis, CA, 95616, USA
| | - Jamie Ahloy-Dallaire
- Département des Sciences Animales, Université Laval, Quebec, QC, G1V 0A6, Canada
| | - Elin M Weber
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Gråbrödragatan 19, 532 31, Skara, Sweden
| | - Brianna N Gaskill
- Animal Sciences Department, Purdue University, 270 S. Russell St., West Lafayette, IN, 47907, USA
| | - Kathleen R Pritchett-Corning
- Office of Animal Resources, Harvard University Faculty of Arts and Sciences, 16 Divinity Ave., Cambridge, MA, 02138, USA
| | - Stephen A Felt
- Department of Comparative Medicine, Stanford University, 300 Pasteur Drive, Stanford, CA, 94305-5342, USA
| | - Joseph P Garner
- Department of Comparative Medicine, Stanford University, 300 Pasteur Drive, Stanford, CA, 94305-5342, USA. .,(By Courtesy), Department of Psychiatry and Behavioral Sciences, Stanford University, 300 Pasteur Drive, Stanford, CA, 94305-5342, USA.
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3
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Turner PV, Hickman DL, van Luijk J, Ritskes-Hoitinga M, Sargeant JM, Kurosawa TM, Agui T, Baumans V, Choi WS, Choi YK, Flecknell PA, Lee BH, Otaegui PJ, Pritchett-Corning KR, Shimada K. Welfare Impact of Carbon Dioxide Euthanasia on Laboratory Mice and Rats: A Systematic Review. Front Vet Sci 2020; 7:411. [PMID: 32793645 PMCID: PMC7387666 DOI: 10.3389/fvets.2020.00411] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 06/09/2020] [Indexed: 12/27/2022] Open
Abstract
Background: There has been increased concern about the suitability of CO2 as a method for euthanasia of laboratory mice and rats, including the potential discomfort, pain or distress that animals may experience prior to loss of consciousness; time to loss of consciousness; best methods for use of CO2; and the availability of better alternatives. These discussions have been useful in providing new information, but have resulted in significant confusion regarding the acceptability of CO2 for rodent euthanasia. In some cases, researchers and veterinarians have become uncertain as to which techniques to recommend or use for euthanasia of laboratory mice and rats. Methods: The International Association of Colleges of Laboratory Animal Medicine (IACLAM) convened a taskforce to examine the evidence for adverse welfare indicators in laboratory rats and mice undergoing CO2 euthanasia using a SYRCLE-registered systematic review protocol. Of 3,772 papers identified through a database search (PubMed, Web of Science, CAB Direct, Agricola, and grey literature) from 1900 to 2017, 37 studies were identified for detailed review (some including more than one species or age group), including 15 in adult mice, 21 in adult rats, and 5 in neonates of both species. Experiments or reports were excluded if they only assessed parameters other than those directly affecting animal welfare during CO2 induction and/or euthanasia. Results: Study design and outcome measures were highly variable and there was an unclear to high risk of bias in many of the published studies. Changes in the outcome measures evaluated were inconsistent or poorly differentiated. It is likely that repeated exposures to carbon dioxide inhalation are aversive to adult rats and mice, based on avoidance behavior studies; however, this effect is largely indistinguishable from aversion induced by repeated exposures to other inhalant anesthetic gasses. Conclusion: There is insufficient evidence to permit an unbiased assessment of the effect of CO2 inhalation during euthanasia on welfare indicators in laboratory mice and rats. Additional well-designed, unbiased, and adequately powered studies are needed to accurately assess the welfare of laboratory mice and rats undergoing euthanasia via CO2 gas.
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Affiliation(s)
- Patricia V. Turner
- Department of Pathobiology, University of Guelph, Guelph, ON, Canada
- Global Animal Welfare and Training, Charles River, Wilmington, MA, United States
| | - Debra L. Hickman
- Laboratory Animal Resource Center, School of Medicine, Indiana University, Indianapolis, IN, United States
| | - Judith van Luijk
- Department of Health Evidence, SYstematic Review Center for Laboratory Experimentation (SYRCLE), Radboud University, Nijmegen, Netherlands
| | - Merel Ritskes-Hoitinga
- Department of Health Evidence, SYstematic Review Center for Laboratory Experimentation (SYRCLE), Radboud University, Nijmegen, Netherlands
| | - Jan M. Sargeant
- Department of Population Medicine, University of Guelph, Guelph, ON, Canada
- Centre for Public Health and Zoonoses, University of Guelph, Guelph, ON, Canada
| | - T. Miki Kurosawa
- Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan
| | - Takashi Agui
- Department of Applied Veterinary Science, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Vera Baumans
- Department of Animals, Science and Society, Utrecht University, Utrecht, Netherlands
| | - Woo Sung Choi
- National New Drug Development Cluster, Woojung Bio, Suwon-si, South Korea
| | - Yang-Kyu Choi
- Department of Laboratory Animal Medicine, College of Veterinary Medicine, Konkuk University, Seoul, South Korea
| | - Paul A. Flecknell
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Byeong H. Lee
- Osong Medical Innovation Foundation, Cheongju, South Korea
| | - Pedro J. Otaegui
- Laboratory Animal Facilities, Autonomous University of Barcelona, Barcelona, Spain
| | - Kathleen R. Pritchett-Corning
- Office of Animal Resources, Harvard University Faculty of Arts and Sciences, Cambridge, MA, United States
- Department of Comparative Medicine, University of Washington, Seattle, WA, United States
| | - Keisuke Shimada
- Animal Resource Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
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Gaskill BN, Stottler AM, Garner JP, Winnicker CW, Mulder GB, Pritchett-Corning KR. Addendum: The effect of early life experience, environment, and genetic factors on spontaneous home-cage aggression-related wounding in male C57BL/6 mice. Lab Anim (NY) 2019; 48:147-148. [PMID: 30911175 DOI: 10.1038/s41684-019-0283-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Brianna N Gaskill
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN, USA.,Charles River, Wilmington, MA, USA
| | - Aurora M Stottler
- Department of Comparative Medicine, Stanford University, Stanford, CA, USA
| | - Joseph P Garner
- Department of Comparative Medicine and, by courtesy, Department of Psychiatry and Behavioural Sciences, Stanford University, Stanford, CA, USA
| | - Christina W Winnicker
- Zuckerman Mind Brain Behavior Institute, Institute of Comparative Medicine, Columbia University, New York, NY, USA.,Charles River, Wilmington, MA, USA
| | | | - Kathleen R Pritchett-Corning
- Charles River, Wilmington, MA, USA. .,Office of Animal Resources, Faculty of Arts and Sciences, Harvard University, Cambridge, MA, USA.
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Landel C, Pritchett-Corning KR. Gene Editing Technologies and Use of Recombinant/Synthetic Nucleic Acids in Laboratory Animals. Appl Biosaf 2018. [DOI: 10.1177/1535676018797353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Boivin GP, Hickman DL, Creamer-Hente MA, Pritchett-Corning KR, Bratcher NA. Review of CO₂ as a Euthanasia Agent for Laboratory Rats and Mice. J Am Assoc Lab Anim Sci 2017; 56:491-499. [PMID: 28903819 PMCID: PMC5605172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 04/19/2017] [Accepted: 05/18/2017] [Indexed: 06/07/2023]
Abstract
Selecting an appropriate, effective euthanasia agent is controversial. Several recent publications provide clarity on the use of CO2 in laboratory rats and mice. This review examines previous studies on CO2 euthanasia and presents the current body of knowledge on the subject. Potential areas for further investigation and recommendations are provided.
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Affiliation(s)
- Gregory P Boivin
- Department of Pathology, Wright State University, Dayton, Veterans Affairs Medical Center, Cincinnati, Ohio
| | - Debra L Hickman
- Laboratory Animal Resource Center, Indiana University, Indianapolis, Indiana;,
| | | | - Kathleen R Pritchett-Corning
- Office of Animal Resources, Harvard University, Cambridge, Massachusetts, Department of Comparative Medicine, University of Washington, Seattle, Washington
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7
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Gaskill BN, Pritchett-Corning KR. Nest building as an indicator of illness in laboratory mice. Appl Anim Behav Sci 2016. [DOI: 10.1016/j.applanim.2016.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Garner JP, Gaskill BN, Pritchett-Corning KR. Two of a Kind or a Full House? Reproductive Suppression and Alloparenting in Laboratory Mice. PLoS One 2016; 11:e0154966. [PMID: 27148872 PMCID: PMC4858245 DOI: 10.1371/journal.pone.0154966] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 04/21/2016] [Indexed: 12/18/2022] Open
Abstract
Alloparenting, a behavior in which individuals other than the actual parents act in a parental role, is seen in many mammals, including house mice. In wild house mice, alloparental care is only seen when familiar sibling females simultaneously immigrate to a male's territory, so in the laboratory, when a pair of unfamiliar female wild mice are mated with a male, alloparenting does not occur because one female will typically be reproductively suppressed. In contrast, laboratory mice are assumed to alloparent regardless of familiarity or relatedness and are therefore routinely trio bred to increase productivity. Empirical evidence supporting the presence of alloparental care in laboratory mice is lacking. Albino and pigmented inbred mice of the strain C57BL/6NCrl (B6) and outbred mice of the stock Crl:CF1 (CF1) were used to investigate alloparenting in laboratory mice since by mating pigmented and albino females with albino males of the same stock or strain, maternal parentage was easily determined. We housed pairs (M:F) or trios (M:2F) of mice in individually ventilated cages containing nesting material and followed reproductive performance for 16 weeks. Females in trios were tested to determine dominance at the start of the experiment, and again 5 days after the birth of a litter to determine if a female's dominance shifted with the birth of pups. Results showed a significant and expected difference in number of offspring produced by B6 and CF1 (p < 0.0001). Pigmented mice nursed and nested with albino pups and vice-versa, confirming empirical observations from many that group nesting and alloparenting occurs in unrelated laboratory mice. When overall production of both individual mice and cages was examined, reproductive suppression was seen in trio cages. Dominance testing with the tube test did not correlate female reproduction with female dominance in a female-female dyad. Due to the reproductive suppression noted in trios, on a per-mouse basis, pair mating outperformed trio mating (p = 0.02) when the measure was weaned pups/female/week. No infanticide was seen in any cages, so the mechanism of reproductive suppression in trio matings may occur before birth.
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Affiliation(s)
- Joseph P. Garner
- Stanford University, Department of Comparative Medicine, and by courtesy, Department of Psychiatry and Behavioral Sciences, Stanford, California, United States of America
| | - Brianna N. Gaskill
- Charles River, Wilmington, Massachusetts, United States of America
- Purdue University Department of Comparative Pathobiology, West Lafayette, Indiana, United States of America
| | - Kathleen R. Pritchett-Corning
- Charles River, Wilmington, Massachusetts, United States of America
- Harvard University Faculty of Arts and Sciences, Office of Animal Resources, Cambridge, Massachusetts, United States of America
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Whitaker JW, Moy SS, Pritchett-Corning KR, Fletcher CA. Effects of Enrichment and Litter Parity on Reproductive Performance and Behavior in BALB/c and 129/Sv Mice. J Am Assoc Lab Anim Sci 2016; 55:387-399. [PMID: 27423144 PMCID: PMC4943608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 10/05/2015] [Accepted: 12/03/2015] [Indexed: 06/06/2023]
Abstract
We examined the effect of adding species-appropriate environmental enrichment items to breeding cages of BALB/cAnNCrl and 129S2/SvPasCrl mice. The 3 enrichment conditions were: 1) cotton nesting material; 2) nesting material plus a paper shelter and rolled paper bedding; and 3) an igloo dome with an exercise wheel in addition to the shelter-group enrichments. We measured litter size, litter survival to weaning age, average pup weight at 21 d, and the interlitter interval to evaluate reproductive performance. A random subset of the first- or second-litter offspring from each enrichment condition and strain was assessed in multiple behavioral tests. Enrichment significantly affected anxiety-like behavior and sociability, with the direction of change dependent on strain and sex. Litter parity had greater effects on some reproductive parameters than did the enrichment condition, and this effect was not solely due to a difference between the first compared with subsequent litters. The significant effects of litter parity on the number of pups born and weaned, female pup weight, and interlitter interval were dependent on the enrichment condition in BALB/c but not 129/Sv mice. Offspring from the first or second litter were included in a generational component to investigate whether enrichment effects on reproduction persist in adult offspring after transfer to a different facility for breeding. Natal cage enrichment had no effect on any reproductive parameter in the transferred mice. Overall, additional enrichment beyond nesting material had a beneficial effect on the interlitter interval in BALB/c mice and on the number of pups weaned in 129/Sv mice.
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Affiliation(s)
- Julia W Whitaker
- Division of Laboratory Animal Medicine, Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, North Carolina, USA.
| | - Sheryl S Moy
- Carolina Institute for Developmental Disabilities and Department of Psychiatry, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Kathleen R Pritchett-Corning
- Research and Professional Services, Charles River Laboratories, Wilmington, Massachusetts, USA; Office of Animal Resources, Harvard University, Faculty of Arts and Sciences, Cambridge, Massachusetts, USA
| | - Craig A Fletcher
- Division of Laboratory Animal Medicine, Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
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Gaskill BN, Pritchett-Corning KR. Effect of Cage Space on Behavior and Reproduction in Crl:CD(SD) and BN/Crl Laboratory Rats. J Am Assoc Lab Anim Sci 2015; 54:497-506. [PMID: 26424247 PMCID: PMC4587617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 08/18/2014] [Accepted: 12/11/2014] [Indexed: 06/05/2023]
Abstract
The 2011 Guide for the Care and Use of Laboratory Animals contains recommendations regarding the amount of cage space for mothers with litters. Literature on cage-space use in breeding rats is sparse. We hypothesized that, if present, differences in behavior and reproduction would be detected between the smallest and largest cages tested. BN/Crl and Crl:CD(SD) rats were assigned to a cage treatment (580 cm(2), 758 cm(2), 903 cm(2), or 1355 cm(2)) and breeding configuration (single: male removed after birth of pups; pair: 1 male, 1 female) in a factorial design for 12 wk. All cages received 20 to 25 g of nesting material, and nests were scored weekly. Pups were weaned, sexed, and weighed between postnatal days 18 and 26. Adult behavior and location in the cage were videorecorded by scan-sampling on the litter's postnatal days 0 through 8 and 14 through 21. Press posture in adults and play behavior in pups were recorded according to a 1-0 sampling method. Differences in reproductive parameters were limited to expected differences related to rat genetic background and weaning weight in pups, which was lowest in the pair-bred CD rats in the smallest cages. Press posture in adults in the smaller cages increased as the pups became mobile. Pair-housed outbred rats in the smallest commercially available cage we tested showed behavioral changes and a lower pup weaning weight. Both laboratory animal scientists and caging manufacturers should address the challenge of providing more biologically relevant cage complexity rather than merely increasing floor space.
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Affiliation(s)
- Brianna N Gaskill
- Department of Comparative Pathobiology, Purdue University, West Lafayette, Indiana, USA; Charles River, Wilmington, Massachusetts, USA.
| | - Kathleen R Pritchett-Corning
- Office of Animal Resources, Faculty of Arts and Sciences, Harvard University, Cambridge, Massachusetts, USA; Charles River, Wilmington, Massachusetts, USA
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Gaskill BN, Pritchett-Corning KR. The Effect of Cage Space on Behavior and Reproduction in Crl:CD1(Icr) and C57BL/6NCrl Laboratory Mice. PLoS One 2015; 10:e0127875. [PMID: 26020792 PMCID: PMC4447268 DOI: 10.1371/journal.pone.0127875] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 04/20/2015] [Indexed: 11/18/2022] Open
Abstract
Recommendations for the amount of cage space required for female mice with litters were first made in the 2011 Guide for the Care and Use of Laboratory Animals. We hypothesized that if a difference in mouse behavior and reproduction exists within the limits of commercially available caging, this difference would be detected between the smallest and largest cages. C57BL/6NCrl and Crl:CD1(Icr) breeding mice were randomly assigned to a cage treatment: LP 18790 (226 cm2); A RC1 (305 cm2); A N10 (432 cm2); T 1291 (800 cm2) and a breeding configuration: single (male removed after birth); pair (1 male + 1 female); or trio (1 male + 2 females) in a factorial design for 12 weeks. All cages received 8-10 g of nesting material and nests were scored weekly. Pups were weaned between post-natal day 18 and 26 and were weighed at weaning. Adult behavior and location in the cage were recorded by scan samples every 30 min over 48 hr of video recorded on PND 0-8 and PND 14-21 when pups were in the cage. Press posture and play behavior were recorded by 1/0 sampling method. Cage space did not significantly alter typical reproductive measures. Pups in the smallest cage played less than in the other cages. Adults in the smallest cage displayed more press posture than in the two largest cages. Mice in the largest cage spent more time under the feeder than in other areas of the cage. Nest score was also the highest in the largest cage. Housing breeding groups of mice in a range of commercially available cage sizes does not affect reproduction but behavioral measures suggest that the smallest cage tested, LP 18790, may be stressful for outbred mice when pups are present.
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Affiliation(s)
- Brianna N. Gaskill
- Purdue University Department of Comparative Pathobiology, West Lafayette, Indiana, United States of America
- Charles River, Wilmington, Massachusetts, United States of America
- * E-mail:
| | - Kathleen R. Pritchett-Corning
- Harvard University Faculty of Arts and Sciences, Office of Animal Resources, Cambridge, Massachusetts, United States of America
- Charles River, Wilmington, Massachusetts, United States of America
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Pritchett-Corning KR, Gaskill BN. Lack of negative effects on Syrian hamsters and Mongolian gerbils housed in the same secondary enclosure. J Am Assoc Lab Anim Sci 2015; 54:261-266. [PMID: 26045450 PMCID: PMC4460937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 06/25/2014] [Accepted: 08/04/2014] [Indexed: 06/04/2023]
Abstract
In cases where different species might be housed in the same room or secondary enclosure, the Guide for the Care and Use of Laboratory Animals recommends that the animals should be behaviorally compatible and have the same health status. Syrian hamsters and Mongolian gerbils, both desert-dwelling rodents, appear to be reasonable candidates for such a combination. This study was undertaken to evaluate whether housing hamsters and gerbils in the same secondary enclosure is an acceptable practice. Weanling and breeding-age hamsters and gerbils were housed in open-topped cages in an isolator for 5 mo; the isolator also contained with nude and haired mice, which acted as sentinels. Cages housing hamsters and gerbils were rotated between species, and dirty bedding was exchanged between species in an effort to transmit microorganisms. In addition, sentinel mice housed in the isolator were supplied with dirty bedding from both hamsters and gerbils. Neither species showed clinical signs of illness, the health status of neither the hamsters nor the gerbils changed significantly, and the sentinel mice acquired only 2 infectious organisms, a Helicobacter species and Staphylococcus aureus. Both hamsters and gerbils bred successfully when housed together in the same isolator, and no infanticide or mortality was seen. Breeding performance did not differ between isolator breeding and barrier breeding. This study supports the housing of hamsters and gerbils in the same secondary enclosure.
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Affiliation(s)
| | - Brianna N Gaskill
- Charles River Laboratories, Wilmington, Massachusetts, USA; Harvard University Faculty of Arts and Sciences
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Henderson KS, Pritchett-Corning KR, Perkins CL, Banu LA, Jennings SM, Francis BC, Shek WR. A comparison of mouse parvovirus 1 infection in BALB/c and C57BL/6 mice: susceptibility, replication, shedding, and seroconversion. Comp Med 2015; 65:5-14. [PMID: 25730752 PMCID: PMC4396924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 05/04/2014] [Accepted: 10/09/2014] [Indexed: 06/04/2023]
Abstract
This study characterized the effects of challenge with a field isolate of mouse parvovirus 1 (MPV1e) in C57BL/6NCrl (B6) and BALB/cAnNCrl (C) mice. We found that C mice were more susceptible to MPV1e infection than were B6 mice; ID50 were 50 to 100 times higher after gavage and 10-fold higher after intraperitoneal injection in B6 as compared with C mice. To evaluate the host strain effect on the pathogenesis of MPV1e, B6 and C mice were inoculated by gavage. Feces and tissues, including mesenteric lymph nodes (MLN), ileum, spleen and blood, were collected for analysis by quantitative PCR (qPCR) to assess infection and fecal shedding and by RT-qPCR to evaluate replication. Peak levels of MPV1e shedding, infection, and replication were on average 3.4, 4.3, and 6.2 times higher, respectively, in C than in B6 mice. Peaks occurred between 3 and 10 d after inoculation in C mice but between 5 and 14 d in B6 mice. Multiplexed fluorometric immunoassays detected seroconversion in 2 of 3 C mice at 7 d after inoculation and in all 3 B6 mice at 10 d. By 56 d after inoculation, viral replication was no longer detectable, and fecal shedding was very low; infection persisted in ileum, spleen, and MLN, with levels higher in C than B6 mice and highest in MLN. Therefore, the lower susceptibility of B6 mice, as compared with C mice, to MPV1e infection was associated with lower levels of infection, replication, and shedding and delayed seroconversion.
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Key Words
- b6, c57bl/6
- c, balb/c
- mfi, median fluorescence intensity
- mfia, multiplexed fluorometric immunoassay
- mln, mesenteric lymph node
- mmv, mouse minute virus
- mpv, mouse parvovirus
- ns1, nonstructural protein 1
- qpcr, quantitative pcr
- r, recombinant
- rn, normalized reporter value
- vp2, virus capsid protein 2
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Affiliation(s)
- Kenneth S Henderson
- Research Animal Diagnostic Services, Charles River, Wilmington, Massachusetts, USA
| | | | - Cheryl L Perkins
- Research Animal Diagnostic Services, Charles River, Wilmington, Massachusetts, USA
| | - Laila A Banu
- Research Animal Diagnostic Services, Charles River, Wilmington, Massachusetts, USA
| | - Steven M Jennings
- Research Animal Diagnostic Services, Charles River, Wilmington, Massachusetts, USA
| | - Brian C Francis
- Research Animal Diagnostic Services, Charles River, Wilmington, Massachusetts, USA
| | - William R Shek
- Research Animal Diagnostic Services, Charles River, Wilmington, Massachusetts, USA
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Shek WR, Smith AL, Pritchett-Corning KR. Microbiological Quality Control for Laboratory Rodents and Lagomorphs. Laboratory Animal Medicine 2015. [PMCID: PMC7150201 DOI: 10.1016/b978-0-12-409527-4.00011-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Mice (Mus musculus), rats (Rattus norvegicus), other rodent species, and domestic rabbits (Oryctolagus cuniculus) have been used in research for over 100 years. During the first half of the 20th century, microbiological quality control of lab animals was at best rudimentary as colonies were conventionally housed and little or no diagnostic testing was done. Hence, animal studies were often curtailed and confounded by infectious disease (Mobraaten and Sharp, 1999; Morse, 2007; Weisbroth, 1999). By the 1950s, it became apparent to veterinarians in the nascent field of comparative medicine that disease-free animals suitable for research could not be produced by standard veterinary disease control measures (e.g., improved sanitation and nutrition, antimicrobial treatments) in conventional facilities. Henry Foster, the veterinarian who founded Charles River Breeding Laboratories in 1948 and a pioneer in the large-scale production of laboratory rodents, stated in a seminar presented at the 30th anniversary of AALAS, “After a variety of frustrating health-related problems, it was decided that a major change in the company’s philosophy was required and an entirely different approach was essential”. Consequently, he and others developed innovative biosecurity systems to eliminate and exclude pathogens (Allen, 1999). In 1958, Foster reported on the Cesarean-originated barrier-sustained (COBS) process for the large-scale production of specific pathogen-free (SPF) laboratory rodents (Foster, 1958). To eliminate horizontally transmitted pathogens, a hysterectomy was performed on a near-term dam from a contaminated or conventionally housed colony. The gravid uterus was pulled through a disinfectant solution into a sterile flexible film isolator where the pups were removed from the uterus and suckled on axenic (i.e., germ-free) foster dams. After being mated to expand their number and associated with a cocktail of nonpathogenic bacteria to normalize their physiology and prime their immune system, rederived rodents were transferred to so-called barrier rooms for large-scale production. The room-level barrier to adventitious infection entailed disinfection of the room, equipment, and supplies, limiting access to trained and properly gowned personnel, and the application of new technologies such as high-efficiency particulate air-filtration of incoming air (Dubos and Schaedler, 1960; Foster, 1980; Schaedler and Orcutt, 1983; Trexler and Orcutt, 1999). The axenic and associated rodents mentioned in the COBS process are collectively classified as gnotobiotic to indicate that they have a completely known microflora. By contrast, barrier-reared rodent colonies are not gnotobiotic because they are housed in uncovered cages and thus acquire a complex microflora from the environment, supplies, personnel, and other sources. Instead, they are described as SPF to indicate that according to laboratory testing, they are free from infection with a defined list of infectious agents, commonly known as an ‘exclusion’ list.
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Pritchett-Corning KR, Prins JB, Feinstein R, Goodwin J, Nicklas W, Riley L. AALAS/FELASA Working Group on Health Monitoring of rodents for animal transfer. J Am Assoc Lab Anim Sci 2014; 53:633-640. [PMID: 25650968 PMCID: PMC4253575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Affiliation(s)
- Kathleen R Pritchett-Corning
- Harvard University Faculty of Arts and Sciences, Cambridge, MA USA; Charles River, Wilmington, MA USA; University of Washington, Seattle, WA, USA
| | - Jan-Bas Prins
- Leiden University Medical Center, Leiden, Netherlands
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Abstract
The minimization and alleviation of suffering has moral and scientific implications. In order to mitigate this negative experience one must be able to identify when an animal is actually in distress. Pain, illness, or distress cannot be managed if unrecognized. Evaluation of pain or illness typically involves the measurement of physiologic and behavioral indicators which are either invasive or not suitable for large scale assessment. The observation of nesting behavior shows promise as the basis of a species appropriate cage-side assessment tool for recognizing distress in mice. Here we demonstrate the utility of nest building behavior in laboratory mice as an ethologically relevant indicator of welfare. The methods presented can be successfully used to identify thermal stressors, aggressive cages, sickness, and pain. Observation of nest building behavior in mouse colonies provides a refinement to health and well-being assessment on a day to day basis.
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Abstract
Some laboratory mice gnaw food pellets without ingesting much of the gnawed material, resulting in the production of waste material called ‘orts’. The fact that this food grinding behavior is not seen in all individuals of a particular strain suggests that it might be abnormal, and thus indicate a welfare concern. Furthermore, the increased rate of feed consumption and cage soiling is undesirable from a husbandry perspective. To try to determine possible motivations for the behavior, and identify potential treatments, outbred Crl:CD1(Icr) mice exhibiting food grinding were selected for one of three treatments placed in the feeder: no enrichment, a chewing device, or sunflower seeds. Both enrichment groups showed a significant decrease ( P < 0.05) in ort production when compared with baseline measurements, but only mice provided with sunflower seeds maintained the decreased rate of food wastage after the treatment was withdrawn. A relationship between body weight and ort production was also found, in that cages with greater average body weights had lower levels of ort production. This suggests that a simple need to gnaw cannot alone explain food grinding, and that a nutritional motivation may also be involved.
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Affiliation(s)
| | - R Keefe
- Research Models and Services, Charles River, Wilmington, MA, USA
| | - JP Garner
- Department of Comparative Medicine, Stanford University, Stanford, CA, USA
| | - BN Gaskill
- Research Models and Services, Charles River, Wilmington, MA, USA
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Pritchett-Corning KR, Clifford CB, Festing MFW. The Effects of Shipping on Early Pregnancy in Laboratory Rats. ACTA ACUST UNITED AC 2013; 98:200-5. [DOI: 10.1002/bdrb.21056] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 02/26/2013] [Indexed: 11/08/2022]
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Gaskill BN, Winnicker C, Garner JP, Pritchett-Corning KR. The naked truth: Breeding performance in nude mice with and without nesting material. Appl Anim Behav Sci 2013. [DOI: 10.1016/j.applanim.2012.10.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Machholz E, Mulder G, Ruiz C, Corning BF, Pritchett-Corning KR. Manual restraint and common compound administration routes in mice and rats. J Vis Exp 2012:2771. [PMID: 23051623 DOI: 10.3791/2771] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Being able to safely and effectively restrain mice and rats is an important part of conducting research. Working confidently and humanely with mice and rats requires a basic competency in handling and restraint methods. This article will present the basic principles required to safely handle animals. One-handed, two-handed, and restraint with specially designed restraint objects will be illustrated. Often, another part of the research or testing use of animals is the effective administration of compounds to mice and rats. Although there are a large number of possible administration routes (limited only by the size and organs of the animal), most are not used regularly in research. This video will illustrate several of the more common routes, including intravenous, intramuscular, subcutaneous, and oral gavage. The goal of this article is to expose a viewer unfamiliar with these techniques to basic restraint and substance administration routes. This video does not replace required hands-on training at your facility, but is meant to augment and supplement that training.
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Pritchett-Corning KR, Clifford CB, Elder BJ, Vezina M. Retinal lesions and other potential confounders of ocular research in inbred mice. Invest Ophthalmol Vis Sci 2012; 53:3764-5. [PMID: 22736716 DOI: 10.1167/iovs.12-10056] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Henderson KS, Dole V, Parker NJ, Momtsios P, Banu L, Brouillette R, Simon MA, Albers TM, Pritchett-Corning KR, Clifford CB, Shek WR. Pneumocystis carinii causes a distinctive interstitial pneumonia in immunocompetent laboratory rats that had been attributed to "rat respiratory virus". Vet Pathol 2012; 49:440-52. [PMID: 22308234 DOI: 10.1177/0300985811432351] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A prevalent and distinctive infectious interstitial pneumonia (IIP) of immunocompetent laboratory rats was suspected to be caused by a putative virus, termed rat respiratory virus, but this was never substantiated. To study this disease, 2 isolators were independently populated with rats from colonies with endemic disease, which was perpetuated by the regular addition of naive rats. After Pneumocystis was demonstrated by histopathology and polymerase chain reaction (PCR) in the lungs of rats from both isolators and an earlier bedding transmission study, the relationship between Pneumocystis and IIP was explored further by analyzing specimens from 3 contact transmission experiments, diagnostic submissions, and barrier room breeding colonies, including 1 with and 49 without IIP. Quantitative (q) PCR and immunofluorescence assay only detected Pneumocystis infection and serum antibodies in rats from experiments or colonies in which IIP was diagnosed by histopathology. In immunocompetent hosts, the Pneumocystis concentration in lungs corresponded to the severity and prevalence of IIP; seroconversion occurred when IIP developed and was followed by the concurrent clearance of Pneumocystis from lungs and resolution of disease. Experimentally infected immunodeficient RNU rats, by contrast, did not seroconvert to Pneumocystis or recover from infection. qPCR found Pneumocystis at significantly higher concentrations and much more often in lungs than in bronchial and nasal washes and failed to detect Pneumocystis in oral swabs. The sequences of a mitochondrial ribosomal large-subunit gene region for Pneumocystis from 11 distinct IIP sources were all identical to that of P. carinii. These data provide substantial evidence that P. carinii causes IIP in immunocompetent rats.
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Affiliation(s)
- K S Henderson
- Research Models and Services, Charles River, 251 Ballardvale St, Wilmington, MA 01887, USA.
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Abstract
Thousands of new genetically modified (GM) strains of mice have been created since the advent of transgenesis and knockout technologies. Many of these valuable animals exist only as live animals, with no backup plan in case of emergency. Cryopreservation of embryos can provide this backup, but is costly, can be a lengthy procedure, and generally requires a large number of animals for success. Since the discovery that mouse sperm can be successfully cryopreserved with a basic cryoprotective agent (CPA) consisting of 18% raffinose and 3% skim milk, sperm cryopreservation has become an acceptable and cost-effective procedure for archiving, distributing and recovery of these valuable strains. Here we demonstrate a newly developed I•Cryo kit for mouse sperm cryopreservation. Sperm from five commonly-used strains of inbred mice were frozen using this kit and then recovered. Higher protection ratios of sperm motility (> 60%) and rapid progressive motility (> 45%) compared to the control (basic CPA) were seen for sperm frozen with this kit in 5 inbred mouse strains. Two cell stage embryo development after IVF with the recovered sperm was improved consistently in all 5 mouse strains examined. Over a 1.5 year period, 49 GM mouse lines were archived by sperm cryopreservation with the I•Cryo kit and later recovered by IVF.
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Affiliation(s)
- Ling Liu
- Genetically Engineered Models and Services, Charles River
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Parkinson CM, O'Brien A, Albers TM, Simon MA, Clifford CB, Pritchett-Corning KR. Diagnosis of ecto- and endoparasites in laboratory rats and mice. J Vis Exp 2011:e2767. [PMID: 21912374 DOI: 10.3791/2767] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Internal and external parasites remain a significant concern in laboratory rodent facilities, and many research facilities harbor some parasitized animals. Before embarking on an examination of animals for parasites, two things should be considered. One: what use will be made of the information collected, and two: which test is the most appropriate. Knowing that animals are parasitized may be something that the facility accepts, but there is often a need to treat animals and then to determine the efficacy of treatment. Parasites may be detected in animals through various techniques, including samples taken from live or euthanized animals. Historically, the tests with the greatest diagnostic sensitivity required euthanasia of the animal, although PCR has allowed high-sensitivity testing for several types of parasite. This article demonstrates procedures for the detection of endo- and ectoparasites in mice and rats. The same procedures are applicable to other rodents, although the species of parasites found will differ.
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Parkinson CM, O'Brien A, Albers TM, Simon MA, Clifford CB, Pritchett-Corning KR. Diagnostic necropsy and selected tissue and sample collection in rats and mice. J Vis Exp 2011:2966. [PMID: 21847084 DOI: 10.3791/2966] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
There are multiple sample types that may be collected from a euthanized animal in order to help diagnose or discover infectious agents in an animal colony. Proper collection of tissues for further histological processing can impact the quality of testing results. This article describes the conduct of a basic gross examination including identification of heart, liver, lungs, kidneys, and spleen, as well as how to collect those organs. Additionally four of the more difficult tissue/sample collection techniques are demonstrated. Lung collection and perfusion can be particularly challenging as the tissue needs to be properly inflated with a fixative in order for inside of the tissue to fix properly and to enable thorough histologic evaluation. This article demonstrates the step by step technique to remove the lung and inflate it with fixative in order to achieve optimal fixation of the tissue within 24 hours. Brain collection can be similarly challenging as the tissue is soft and easily damaged. This article demonstrates the step by step technique to expose and remove the brain from the skull with minimal damage to the tissue. The mesenteric lymph node is a good sample type in which to detect many common infectious agents as enteric viruses persist longer in the lymph node than they are shed in feces. This article demonstrates the step by step procedure for locating and aseptically removing the mesenteric lymph node. Finally, identification of infectious agents of the respiratory tract may be performed by bacterial culture or PCR testing of nasal and/or bronchial fluid aspirates taken at necropsy. This procedure describes obtaining and preparing the respiratory aspirate sample for bacterial culture and PCR testing.
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Abstract
For both scientific and animal welfare reasons, training in basic surgical concepts and techniques should be undertaken before ever seeking to perform surgery on a rodent. Students, post-doctoral scholars, and others interested in performing surgery on rodents as part of a research protocol may not have had formal surgical training as part of their required coursework. Surgery itself is a technical skill, and one that will improve with practice. The principles of aseptic technique, however, often remain unexplained or untaught. For most new surgeons, this vital information is presented in piecemeal fashion or learned on the job, neither of which is ideal. It may also make learning how to perform a particular surgery difficult, as the new surgeon is learning both a surgical technique and the principles of asepsis at the same time. This article summarizes and makes recommendations for basic surgical skills and techniques necessary for successful rodent surgery. This article is designed to supplement hands-on training by the user's institution.
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Mulder GB, Pritchett-Corning KR, Gramlich MA, Crocker AE. Method of feed presentation affects the growth of Mongolian gerbils (Meriones unguiculatus). J Am Assoc Lab Anim Sci 2010; 49:36-39. [PMID: 20122314 PMCID: PMC2824965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Revised: 06/23/2009] [Accepted: 07/09/2009] [Indexed: 05/28/2023]
Abstract
The Animal Welfare Regulations, which define legal requirements for the care and use of gerbils in research and testing, and the Guide for the Care and Use of Laboratory Animals describe feeding practices for several species of rodents but not Mongolian gerbils (Meriones unguiculatus). To investigate whether the method of feed presentation affected reproduction and growth of gerbils, we compared the reproductive performance and rate of growth of gerbils fed on the cage floor, by hopper (J-feeder), or by wire-bar cage lid. Reproductive parameters of 10 breeding pairs for each method of feeding were followed for 63 d and did not differ between methods. To investigate the effect of feeding method on weight gain in juvenile gerbils, groups of 80 male and 80 female weanling gerbils per feeding method were fed for 5 consecutive weeks after weaning and weighed weekly. Gerbils fed on the cage floor and by means of J-feeders were significantly heavier than were those fed by using a wire-bar top. Our findings indicate that feeding gerbils by using J-feeders or on the cage floor are both acceptable practices.
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Affiliation(s)
- Guy B Mulder
- Research Models and Services, Charles River, Wilmington, Massachusetts, New York, USA.
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Pritchett-Corning KR, Chang FT, Festing MFW. Breeding and housing laboratory rats and mice in the same room does not affect the growth or reproduction of either species. J Am Assoc Lab Anim Sci 2009; 48:492-498. [PMID: 19807969 PMCID: PMC2755018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 04/16/2009] [Accepted: 05/17/2009] [Indexed: 05/28/2023]
Abstract
Few data exist regarding the effects of long-term housing of rats and mice in the same secondary enclosure. Historical reproductive and growth data were compared for colonies of mice and rats maintained in open-topped cages in either single-species or dual-species barrier rooms. This analysis included reproductive parameters (litter size at birth, litter size at weaning, and pups missing at weaning) collected from 33 colonies of mice comprising 500 to 38,500 breeding females and 28 colonies of rats totaling 350 to 4,600 breeding females, and representative samples from 28 colonies of each species were analyzed for weight gain from weaning to adulthood. The presence or absence of the other species was not associated with statistically significant differences in weight gain or any of the reproductive parameters. These results suggest that breeding colonies of rats and mice of the same health status can be housed in the same room without a negative effect on the growth and reproduction of either species.
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Abstract
Periodic health screening of rodents used in research is necessary due to the consequences of unwanted infections. One determinant of the risk of infection for any given agent is its prevalence; other factors being equal, a prevalent agent is more likely than a rare one to be introduced to a research facility and result in infection. As an indicator of contemporary prevalence in laboratory populations of rats and mice, the rate of positive results in the samples received at a major commercial rodent diagnostic laboratory was compiled for this paper. Although samples from laboratory rodent vendors have been excluded, results are tabulated from samples from more than 500,000 mice and 80,000 rats submitted over several years from pharmaceutical, biotechnology, academic, and governmental institutions in North America and Europe, allowing meaningful determination of which agents are common in the research environment versus which agents are rare. In mice, commonly detected infectious agents include mouse norovirus, the parvoviruses, mouse hepatitis virus, rotavirus, Theiler's murine encephalomyelitis virus, Helicobacter spp., Pasteurella pneumotropica, and pinworms. In rats, commonly detected infectious agents include ‘rat respiratory virus’, the parvoviruses, rat theilovirus, Helicobacter spp., P. pneumotropica, and pinworms. A risk-based allocation of health-monitoring resources should concentrate frequency and/or sample size on these high-risk agents, and monitor less frequently for the remaining, lower-risk, infectious agents.
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Affiliation(s)
- Kathleen R Pritchett-Corning
- Research Animal Diagnostic Services, Charles River Laboratories, Domaine des Oncins, BP 0109, 69592 L'arbresle Cedex, France
| | - Janice Cosentino
- Research Animal Diagnostic Services, Charles River Laboratories, 251 Ballardvale Street, Wilmington, MA 01887, USA
| | - Charles B Clifford
- Research Animal Diagnostic Services, Charles River Laboratories, 251 Ballardvale Street, Wilmington, MA 01887, USA
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Pritchett-Corning KR. Euthanasia of neonatal rats with carbon dioxide. J Am Assoc Lab Anim Sci 2009; 48:23-27. [PMID: 19245746 PMCID: PMC2694698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 06/24/2008] [Accepted: 07/21/2008] [Indexed: 05/27/2023]
Abstract
Exposure to CO(2) is a common method used to euthanize rodents in biomedical research and rodent production. The purpose of this study was to determine the length of CO(2) exposure required to euthanize neonatal rats (0 to 10 d old). Multiple groups of rats were exposed to 100% CO(2) for 5 to 60 min. After CO(2) exposure, rats were placed in room air for 20 min to allow for possible recovery. No difference was found in comparing 1 inbred strain and 1 outbred stock of rats. Time to death varied inversely with the age of the animals, requiring as long as 35 min on the day of birth. The time to death decreased steadily with increasing age, with 100% of the rats euthanized after 5 min of CO(2) exposure at 10 d of age. The time required for 100% mortality decreased by 3 min for every 1 d increase in age between days 0 and 10.
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