Bourn tested the ankle with several running drills before batting practice Monday and was somewhat encouraged by the results.
"I didn't really cut on it too much, but I'm going to cut on it during [batting practice] to see how it feels," he said. "It wasn't too, too bad. I feel like I'm walking better. When I get up in the morning, it's not too sore. That's a good thing."
Still, Bourn's limited availability puts the Astros in somewhat of a bind, because it leaves them short an outfielder. With Darin Erstad playing every day in Bourn's place in center, manager Cecil Cooper is missing a major late-game defensive weapon and doesn't have a solid backup plan should he need someone other than Erstad.
Cooper named Ty Wigginton, Lance Berkman and David Newhan as emergency outfielders, but none of the three have had any practice or playing time in the outfield this year. If he had to, Cooper could move Hunter Pence to center.
How much longer can the Astros play a man short, and would the Astros consider a disabled list stint for Bourn to make room for a more able-bodied outfielder?
"I don't know," Cooper said. "If it doesn't get any better here soon then, yeah, we'll have to do something. It does kind of limit you what you can do."
In other injury news, Mark Loretta was available to play Monday, even though he's not quite recovered from the bruised thigh he suffered during his double slide with Pence on Saturday.
"It's better," Loretta said. "I'll be OK."
Alyson Footer is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.