That moved Howell to 23 2/3 innings since last allowing a run, which he did on June 13 against the Mets. He then pitched another scoreless inning in Saturday night's game against the Angels to get to 24 2/3.
Howell missed all of the 2010 season after shoulder surgery, which added significance to his streak.
"I was just thinking about how bad it got last year," said Howell, referencing his up-and-down 2011 season. "My wife witnessed it in the stands. So it's funny for us to look back and kind of clean our hands off from all of that and say that now we can move forward and keep it rolling. It's the first time in a while where it's fun to look back."
Shields sang Howell's praises.
"It's amazing, I'm proud of him," Shields said. "... I couldn't be more proud of him for the way he's come back after surgery and all of that stuff."
Added Rays manager Joe Maddon: "I'm so happy for him. I mean here's a guy who pretty much was a huge contributor to the 2008 World Series run. Eventually undergoes shoulder surgery, has a tough time with it, and struggled. And all of a sudden he's put it back together. And actually a little better version of what he had been. I'm really happy for him personally."
Howell's streak ranks as the longest active streak in baseball, ahead of the Reds' Aroldis Chapman (22 2/3) and the Phillies' Cole Hamels (22), who started Saturday night.