Posture and movement characteristics of forward and backward walking in horses with shivering and acquired bilateral stringhalt.

This study delves into the investigation of the posture and movement characteristics in horses experiencing shivering and a simultaneous condition of acquired bilateral stringhalt, specifically during forward and backward walking. The study relies on qualitative video analysis to ascertain the peculiarities of movement, timing, and pattern of limb flexion and extension.

Objective and Methods

• The primary objective of the research was to study and characterize the movement variations in horses exhibiting shivering symptoms in contrast to healthy (control) horses and horses with acquired bilateral stringhalt.
• The research methodology involved qualitative video analysis, where videos showcasing horses walking forward and backward, furnished by the owners and authors, were inspected to detect any signs of hyperflexion, hyperextension, and distinctive postural abnormalities of hindlimbs.
• The pattern and timing of the vertical displacement of a hindlimb in one stride unit is observed and compared among control, shivering and stringhalt cases.

Results

• The analysis led to a classification of the shivering cases into three categories. Shivering-hyperextension (n = 13) displayed hyperextension while backing and lifting the limb. Shivering-hyperflexion (n = 27) made the horses show hindlimb hyperflexion and abduction while walking backward. And shivering-forward hyperflexion (n = 4), which was somewhat similar to shivering-HF, but displayed intermittent hyperflexion and abduction during forward walking.
• Horses with shivering-HF, shivering-FHF, and stringhalt (n = 7) had a prolonged swing phase during backward walking compared to control horses and horses with shivering-HE.
• During the swing phase of forward walking, horses with stringhalt showed a rapid rise to adducted hyperflexion of the hindlimb, which was different from a sudden descent of the hindlimb after the abducted hyperflexion found in shivering-FHF horses.

Conclusions

• Shivering affects the backward walking of horses, causing hyperextension or hyperflexion of hindlimbs and, over time, may also induce intermittent abducted hyperflexion during forward walking.
• Shivering-HF and shivering-FHF are closely similar to acquired bilateral stringhalt during backward walking. However, they can be distinguished by observing the presence of hyperflexion during forward walking in stringhalt cases, and an acute onset of more consistent, rapidly ascending, hyperflexed, adducted hindlimb gait in case of shivering-FHF.