"This is a huge disappointment for Filipe and for us because he's been a big, big player. The supporters have taken to him," he told BBC WM.
"He has contributed immensely and will be a loss.
"But the rest of us have got to push on regardless and hopefully by the time Filipe's ready to pull his boots back on and play we'll be a Premier League side," Mowbray added.
Teixeira has returned to Portugal for a second medical opinion, but is expected to have reconstructive surgery to fix the damage.