title: Retained fetal membranes in C57BL/6NCrl mice: description of clinical case presentations and related epidemiologic findings.
abstract: During a triinstitutional study to test whether individually ventilated caging systems impaired welfare and reproduction relative to static housing systems, varying numbers (2 to 7) of discoid-shaped, fleshy structures were found in utero of 17 postpartum female mice on study. Further  investigation revealed these structures to be retained fetal membranes (RFM). A point prevalence of 24.3% was calculated based on a total population of 70 postpartum female mice on study. This finding was preceded by 3 typical clinical presentations, which are described here. We designed a  case-control matched cross-sectional epidemiologic study to identify associated risk factors and antemortem indicators of RFM. Housing on the bottom shelves and attachment to the rack systems were factors associated with a diagnosis of the condition. In addition, neutrophilia, monocytosis,  lymphopenia, and decreasing hematocrit values were associated with the diagnosis of RFM. These results confirmed that a CBC can be a useful antemortem screening test for the identification of affected mice. We conclude that RFM are likely an incidental finding although they may present concurrent  with other pregnancy complications.
authors.affiliation: Department of Comparative Pathobiology, Purdue University, West Lafayette, USA. jensvm2001@yahoo.com
authors.forename: Jenelle K
authors.initials: JK
authors.lastname: Johnson
authors.forename: Tracy H
authors.initials: TH
authors.lastname: Vemulapalli
authors.forename: William G
authors.initials: WG
authors.lastname: Van Alstine
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Roberts
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Garner
authors.forename: Debra L
authors.initials: DL
authors.lastname: Hickman
mesh_terms: D000818:Animals; D001772:Blood Cell Count; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005321:Extraembryonic Membranes / Q000473:pathology*; D005260:Female; D006400:Hematocrit; D006799:Housing, Animal; D016013:Likelihood Functions; D016015:Logistic Models; D051379:Mice; D008810:Mice, Inbred C57BL; D022423:Myeloid Cells; D049590:Postpartum Period; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary*; D015995:Prevalence; D012307:Risk Factors; D012376:Rodent Diseases / Q000453:epidemiology* / Q000473:pathology*