Nat. Protoc. 6, 1183–1191 (2011); doi:10.1038/nprot.2011.361; published online 21 July 2011; corrected after print 17 December 2014

In the version of this article initially published, there was some confusion over the interpretation of the sentence “Further, defeats should be run under constant veterinary evaluation and with full approval of all necessary institutional review boards and standards.” For added clarity, the sentence was changed to read “Further, defeats should be run with full approval of all necessary institutional review boards and standards.” The error has been corrected in the HTML and PDF versions of the article.