Patrick Kane and Brent Seabrook each had a goal and two assists, and the Blackhawks beat the Florida Panthers 3-2 on Thursday night in their first game since top defenseman Duncan Keith had right knee surgery.Artem Anisimov also scored for the Stanley Cup champions, and Corey Crawford made 16 saves while improving to 5-1 in seven career starts against Florida.Keith had a meniscal tear repaired on Tuesday, sidelining the two-time Norris Trophy winner for four to six weeks. It could be a huge blow for the Blackhawks, who were already thin on defense and play in one of the NHL’s best divisions, but they responded with a smart, measured performance on the first night of Keith’s extended absence.Jaromir Jagr and Vincent Trocheck scored for Florida, which has dropped three in a row. Roberto Luongo made 24 saves.