A pet drinking aid is disclosed that includes a cap defining an axial passage therewithin. Preferred embodiments of the cap include securing means for detachably securing the cap to a fluid container and an inwardly directed flange. The securing means may include helical threads, an elastomeric sleeve or the like. The cap further includes a ball positioned within the axial passage of said cap and, in a preferred embodiment, biasing means mounted relative to the cap within the axial passage. The biasing means advantageously engages the ball to bias the ball toward the inwardly directed flange. The ball is preferably captured within the axial passage between the inwardly directed flange and the biasing means, and the ball is capable of rotatable movement and limited axial movement against the bias of the biasing means. The biasing means may include a compression spring, a foam member or the like. In an alternative embodiment, the biasing means is omitted and the cap includes an inwardly directed ridge extending from the caps inner surface at an axial location intermediate the first and second ends of the cap.
