The Hornets have also confirmed that striker Moses Ashikodi's loan spell at Bradfoed City is over as he broke his leg playing for the League One side against Brighton at the weekend.
"It's always upsetting to receive such news and obviously it's devastating for the two lads to have picked up such serious injuries," manager Aidy Boothroyd has said.
"They're both young players at a new club and along with me were looking forward to bright futures with us here at Watford.
"But one thing I know is that these sort of blows can often make you stronger, I hope that will be the case with both of them, and they will return fitter and tougher for us."