Storm Over Warlock by Andre Norton

The musty stench was so strong that Shann could no longer fight the demands of his outraged stomach. He rolled on his side, retching violently until the sour smell of his illness battled the foul odor of the ship. His memories of how he had come into this place were vague; his body was a mass of dull pain, as if he had been scorched. Scorched! Had the Throgs used one of their energy whips to subdue him? The last clear thing he could recall was that slow withdrawal down the cleft inside the skull rock, the Throg not too far away -- the sound from the entrance.

A Throg prisoner! Through the pain and the sickness the horror of that bit doubly deep. Terrans did not fall alive into Throg hands, not if they had the means of ending their existence within reach. But his hands and arms were caught behind him in an unbreakable lock, some gadget not unlike the Terran force bar used to restrain criminals, he decided groggily.