Bowe is sick -- nothing more -- a league source told NFL Network insider Jason La Canfora. The wide receiver fully intends to play Sunday against the Ravens.
Still, the Chiefs made roster moves, signing free-agent wide receiver Kevin Curtis, who has played in 81 games with the Miami Dolphins, Philadelphia Eagles and St. Louis Rams. They also placed defensive back Donald Washington on season-ending injured reserve and added tight end Cody Slate to the practice squad.
Sticking to the team's policy of not commenting on player availability, Haley declined to speculate on whether Waters or Bowe would be ready for Sunday's game.
"I just go by today," the coach said. "Today, they were not able to go."
Losing Bowe would really hurt -- he is the Chiefs' only consistent threat at wide receiver and was selected to his first Pro Bowl after making 72 catches for 1,162 yards and a league-best 15 touchdowns. Between Oct. 17 and Nov. 28, he also set a team record with at least one touchdown catch in seven consecutive games.
If Curtis is pressed into service Sunday, Haley said he was confident the veteran could do the job.
"We've done a lot of research on this guy throughout the year. But it's our effort to always make progress and create competition," Haley said. "He knows this system. What they're running in Miami is very similar terminology. That's an edge."
Cassel said Bowe missing a day or two of practice shouldn't disrupt their timing.
"We've been together for 17 weeks now, or whatever it's been, and hopefully he's back sooner than later and he rests up and he's back on the field, and we're able to continue to work together," Cassel said. "From a timing standpoint, I think I understand Dwayne's body language, his ability to run certain routes. I think we'll be fine."
The Associated Press contributed to this report.