Kershaw had not allowed a run since July 5 against the New York Mets. The major league record is 59 innings, set by Orel Hershiser in 1988 with the Dodgers.
Kershaw never got comfortable after the first-inning homer, allowing four earned runs on nine hits in six innings. The Dodgers lost onPedro Alvarez's walk-off single in the 10th inning.
"It was a tough one," Kershaw said after the game. "I struggled all the way through, pretty much, and give the Pirates credit. They did a good job battling me the whole night, and I just didn't really have good stuff."
Dodgers right-hander Zack Greinke had a 43-inning scoreless streak earlier this season, which ended June 26 against the Mets.
Information from The Associated Press was used in this report.