The Washington Post still has the article up:
https://www.washingtonpost.com/national/health-science/a-new-model-of-empathy-the-rat/2011/12/08/gIQAAx0jfO_story.html
And here’s the science article that prompted it:
https://www.science.org/doi/10.1126/science.1210789
and here’s an old archive.org copy of it before the Washington Post started blocking the wayback machine:
https://web.archive.org/web/20140114012833/http://www.washingtonpost.com/national/health-science/a-new-model-of-empathy-the-rat/2011/12/08/gIQAAx0jfO_story.html