title: American and Japanese rats of the same species: are they same?
abstract: BACKGROUND
  We have previously reported a chronic acid reflux esophagitis model using Japanese Wistar male (JWM) rats. The aim of this study is to discuss unexpected differences encountered within the same species bred in different countries.
  
  
  METHODS
  In JWM rats via a midline laparotomy the limiting ridge of the stomach was ligated and the duodenum was covered with a small piece of an 18 Fr. catheter. We subsequently tried to reproduce the same model using American Wistar male (AWM) and subsequently with female (AWF) rats.
  
  
  RESULTS
  The 3-wk survival rate of AWM rats (30%) was significantly lower than for JWM rats (90%) due to differences in growth curve and eating behaviors. On the other hand, the growth curve of AWF rats was similar to JWM rats. Still, the 3-wk survival rate was only 40% mainly due to different eating patterns. Since then we have modified our postoperative care to include restricted access to food and other objects and have achieved a 3-wk survival of 80%, which is the same as JWM rats.
  
  
  CONCLUSIONS
  Growth curve and eating behavior of rats from different countries exhibit significant differences even within the same species. It is important that such differences be taken into account when reproducing animal models created elsewhere.
authors.affiliation: Department of Surgery, Creighton University Medical Center, Omaha, Nebraska 68131-2197, USA.
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Yano
authors.forename: Rudolf J
authors.initials: RJ
authors.lastname: Stadlhuber
authors.forename: Kazuto
authors.initials: K
authors.lastname: Tsuboi
authors.forename: Nobuo
authors.initials: N
authors.lastname: Omura
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Kashiwagi
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Yanaga
authors.forename: Sumeet K
authors.initials: SK
authors.lastname: Mittal
mesh_terms: D000818:Animals; D004386:Duodenum / Q000601:surgery; D004941:Esophagitis / Q000601:surgery* / Q000662:veterinary; D005260:Female; D007564:Japan; D008297:Male; D051381:Rats / Q000145:classification / Q000235:genetics*; D017208:Rats, Wistar; D013045:Species Specificity; D013270:Stomach / Q000601:surgery*; D013514:Surgical Procedures, Operative / Q000401:mortality / Q000706:statistics & numerical data; D015996:Survival Rate; D017741:Survivors; D014481:United States