Abstract: A thumb operated balling gun for discharging a bolus within the throat of an aminal is disclosed. A plunger, responsive to the movement of an operator's thumb, is axially slidable within a barrel having a plurality of resilient arms extending therefrom. The resilient arms, in combination with the barrel, are particularly configured to avoid damaging the delicate tissues within the mouth and the throat of the animal. A collar, circumscribing the plunger and contacting the interior surface of the resilient arms on retraction of the plunger forces the resilient arms to open and permit insertion of a bolus within the grasp of the arms. After insertion of the bolus, slight extension of the plunger disassociates the collar from the arms, whereby the latter close upon the bolus and retain it in place. Further extension of the plunger ejects the bolus from within the grasp of the arms and into the throat of the animal.