The 44-year-old Testaverde, the NFL's oldest quarterback, missed Sunday's 20-7 loss to the Tennessee Titans because of tendinitis in his right Achilles tendon.
He joined the Panthers last month after Jake Delhomme was placed on the injured reserve list following right-elbow surgery.
Coach John Fox was non-committal on whether he would start Testaverde or David Carr -- who suffered a concussion in Sunday's contest, against Atlanta -- or whether another quarterback would be signed.
"As we move forward and evaluate it, it is truly day to day," Fox said on Carolina's Web site. "I wouldn't say that's not a possibility."
The injury-plagued Panthers Tuesday placed linebacker Dan Morgan on IR because of an injured right Achilles tendon, suffered in the third quarter of Carolina's game at Atlanta Sept. 23.