Full-back Stuart returned home from the British & Irish Lions tour of New Zealand prematurely with a face injury and has had an underlying shoulder issue operated on. He is expected to remain on the sidelines for four to six months.
Glasgow skipper Jonny has had surgery on a wrist injury after returning home from Scotland's Summer Tour. The 23-year-old second-row also faces a four-to-six-month recovery period.
Ratuniyara ruptured his Achilles in Warriors pre-season training and has successfully undergone surgery at BMI Ross Hall Hospital in Glasgow.
The 26-year-old winger, who is on a partnership contract with Currie Chieftains, is expected to be out of action for six to nine months.
The club would like to thank BMI Ross Hall Hospital for their support.