The gaits of domestic kittens between one week and six months of age were analysed according to the methods of Hildebrand (1976, 1977) to determine how gait preference and performance changes during normal ontogeny. Allometric growth of the limb segments was measured so that mechanical effects on gait behaviour could be described. Gait behaviour during ontogeny follows a pattern of increasing precision and diversity that parallels the attainment of neuromuscular maturity: one- and two-week old kittens use very slow, stable walking gaits. By three weeks of age, walking patterns are more diverse and kittens begin to trot. At four weeks, animals are trotting more readily and begin to use slow gallops. Neuromuscular maturity is attained by about six weeks of age and these animals use all of the gaits common to adults. Evidence that the ontogeny of behaviour reflects a recapitulation of neural evolution is discussed.
Important mechanical changes occur in the posture and limb proportions of kittens during ontogeny that markedly affect their gait performance. Until six weeks of age, kittens are plantigrade or semiplantigrade, resulting in functionally shortened limbs. The foot segments were found to be relatively long in kittens up to 12 weeks of age. While plantigrade, these long feet provide large bases of support, but are awkward to move heel-to-toe, and may contribute to the need for the most stable footfall patterns in young kittens. With fully digitigrade posture achieved between six to eight weeks of age, the long foot segments result in relatively longer limbs. At eight weeks, this is reflected in their preference for the pace while walking to avoid interference between ipsilateral limbs. These behavioural modifications of gait patterns in response to transient mechanical constraints support a facultative view of neural control.