Temporal gait parameters in the alpaca and the evolution of pacing and trotting locomotion in the Camelidae

Abstract

Alpacas are increasingly popular as domesticated companion and commercial animals. Their footfall patterns, however, are not well documented. It would be fascinating to know if artificial selection has changed alpacas' locomotor patterns from the ancestral condition in the vicu˜na. Some members of the Camelidae pace rather than trot, but the gaits of most species have not been studied quantitatively. Thus, investigating alpacas' gaits might contribute to understanding the factors influencing gait choice and evolution. We aimed to quantify the temporal footfall patterns of alpacas to determine observed gaits and to describe gait parameters as a function of speed. Kinematic data (3D motion capture) of locomotor patterns over a range of speeds were collected from four alpacas. We quantified the influence of speed on stance time, swing time, stride time (and frequency), duty factor and stride length, and created gait diagrams for symmetrical and asymmetrical gaits. Alpacas moved using lateral sequence walks, mainly lateral couplets walks and runs with some lateral sequence, singlefoot footfall patterns. Remarkably, the alpacas never truly paced or trotted. At faster speeds, they switched to asymmetrical gaits, predominantly transverse gallops. With increasing speed, stance and stride times decreased, and stride frequencies and stride length increased. Swing times decreased slightly with speed for symmetrical gaits, and a tendency towards an increasing swing time was evident in asymmetrical gaits. It is still uncertain why quadrupeds choose particular gaits and intriguingly, extant camelids (alpacas, dromedary camels) do not trot. The apparent absence of pacing in alpacas deserves further investigation in an experimental and comparative framework. Yet, this absence seems inherited from their vicu˜na ancestors, indicating that pacing gaits may not be ancestral or common for Camelidae. Future studies should include kinetic and anatomical data to provide insight into wholebody mechanics, and include other unstudied species such as guanacos and vicu˜nas.

Grizzly bear (Ursus arctos horribilis) locomotion: gaits and ground reaction forces

“…It has been suggested that this gait limits interference between limbs in animals with long limbs (Dagg, 1973). A study of alpacas found that these animals use lateral sequence walks at slow speeds (Fr >0.68; Pfau et al, 2011), which is similar to the results of our study despite the distinct evolutionary history and morphological differences between bears and alpacas. The trot and the pace require forelimbs and hindlimbs of equal length, with a straight short back (Dagg, 1973); bears are characterised as having a relatively long, sloping back and this may be limiting their use of these gaits.…”

MRI evaluation of spontaneous intervertebral disc degeneration in the alpaca cervical spine

“…All the alpacas in this study were anecdotally found to be asymptomatic for pain and did not exhibit obvious clinical signs of pain or abnormality of gait or neck movement. Each alpaca was observed to have a symmetrical gait with a lateral sequence footfall pattern when walking that was assessed to be sound, clinically normal, and not suffering from any orthopedic disease . Several IVDs presented decreased MR signal intensity and had visible defects associated with the disc structure, including disc protrusions ( n = 9), disc prolapse ( n = 5), spinal cord impingement ( n = 1), and mild spinal cord deviation ( n = 3), as shown in Figure .…”

Descripción de las huellas de camélidos y félidos de la localidad Pie de Vaca, Cenozoico Tardío de Puebla, centro de México y algunas consideraciones paleobiológicas

“…El canter es un movimiento semejante al galope, aunque relativamente más lento, en el que las extremidades anterior derecha/ posterior izquierda se mueven juntas en una fase (Webb, 1972;Collins y Stewart, 1993;Kienapfel et al, 2014). La velocidad promedio de los camélidos de Pie de Vaca es mayor en comparación a la velocidad promedio de una llama o una alpaca al caminar, la cual es de 1.13 m/s y 0.97 m/s respectivamente (Pfau et al, 2011;Kienapfel et al, 2014). Con base en esto, se propone que los camélidos que generaron los rastros de Pie de Vaca estaban realizando un caminar rápido similar al canter.…”