The "dog paddle": Stereotypic swimming gait pattern in different dog breeds.

The term "dog paddle" has been applied to the swimming behavior of various terrestrial and aquatic species. Dog paddling refers to a form of drag-based, paddle propulsion in which the limbs are oriented underneath the body and moved through an arc. Despite the ubiquity of the term, there has been no analysis of the swimming kinematics of dogs. Underwater video was recorded of surface swimming dogs (velocity: 0.4-1.1 m/s) for eight individuals from six breeds, ranging in size from Yorkshire Terrier (3.6 kg) to Newfoundland dog (63.5 kg). The quadrupedal paddling stroke was analyzed to determine kinematics and coordination of the limbs. The paddling stroke represented a modified terrestrial gait, which was outside typical gaits for terrestrial locomotion by dogs. Stroke frequency decreased with increasing body size. The stroke cycle consisted of power and recovery phases. During the power phase, digits of the paw were abducted and the forelimb was swept posteriorly until perpendicular to the body. In the recovery phase, digits were adducted while the brachium was retracted anteriorly and the manus supinated. The power phase was about 34% of stroke cycle and shorter than the recovery phase for both fore and hindlimbs. Maximum velocity during the power phase was greater than the recovery phase. The modified terrestrial gait used for swimming by dogs appears to be stereotypic among breeds, whereas terrestrial locomotion in dogs shows substantial variation in gait. Without constraints imposed by gravity and substrate contact, swimming dogs can utilize a gait profile different from terrestrial gaits. SUMMARY STATEMENT: Despite the ubiquity of the term "dog paddle" to describe the swimming motions of animals, this is the first time that the swimming motions of dogs have been analyzed.