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Incidences of embryo-fetal loss (EFL, between gestation day [GD] 20 and 140), stillbirth (SB, after GD140), gestation length, and clinical pathology parameters are critical in pre- and post-natal developmental (PPND) studies. Historical control data of these parameters in the Cynomolgus monkey (Macaca fascicularis) model between our “old” historical control data, obtained from 31 developmental and reproductive studies (including 18 PPND studies) conducted between 2005 to 2011 (N = 469 at GD20), and data from our current (“new”) PPND study (N=36) were compared. All maternal animals were single-housed in the old data set and socially-housed (two or three animals in a four-pack caging unit) in the new data set.

Incidence of EFL was 17.1% (mean ±SD = 16.3 ±8.1%; Min to Max = 0.0 to 31.3%) in the single-housed data set and 8.3% in the socially-housed data set. Incidences in the first, second, and third trimesters were 12.8, 2.3, and 1.9%, respectively, in the single-housed data set and 5.6, 0.0, and 2.8%, respectively, in the socially-housed data set. Incidence of SB was 14.7% (14.4 ±9.3%; 0.0 to 33.3%) in the single-housed data set and 6.1% in the socially-housed data sets. Mean gestation length was 158 ±9 days in the single-housed data set and 161 ±6 days in the socially-housed data set. Infant survival rate at Day 7 of post-birth was 68.6% (68.5 ±10.7%; 47.6 to 86.7%) in the single-housed data set and 83.3% in the socially-housed data set. Common clinical pathology parameters collected during the gestation and lactation periods (from maternal animals and infants) were also comparable between the two data sets.

The EFL/SB data, gestation length, infant survival ratio, and common clinical pathology parameters obtained from socially-housed animals were generally comparable with those obtained from single-housed animals. Therefore, we consider that both data sets can be combined and historical control data in PPND studies can be accumulated further despite variances in housing conditions. Although incidences of EFL and SB in socially-housed animals were somewhat lower than that of single-housed animals and in resulted higher infant survival ratio at PND7, we cannot make any definitive conclusion at this point regarding the benefit of social housing of pregnant/lactating animals due to a limited data set obtained thus far.


S. Oneda1, N. Lalayeva1, J. Reynolds1, G. Von Scherr1, M. Vegarra1, S. Glaza1, T. Rogers1, and R. Nagata2

1SNBL USA, Ltd., Everett, WA, USA;  2Shin Nippon Biomedical Laboratories, Ltd., Tokyo, Japan