Hindlimb response to tactile stimulation of the pastern and coronet.

The research investigated the effects of tactile stimulation on horse hindlimbs, finding that the introduction of lightweight stimulators alters the mechanics of a stepping horse to increase flexion (bending) of the hindlimb joints and the positive work of the hip and tarsal muscles, potentially serving as a therapeutic mechanism in physiotherapy and rehabilitation.

Objective of the Research

• The research aimed to study the impact of tactile stimulators on the hindlimbs of horses. Specifically, the researchers wanted to understand how these stimulators might affect the flexions of the hindlimb joints and how much work the hip and tarsal muscles performed.

Methodology Used

• The researchers used nine healthy, non-lame horses for the experiment. Each horse was asked to trot four times, with and without tactile stimulators weighing 55 grams attached loosely around their hind pasterns (the slim area of the leg just above the hoof).
• They measured the height of the flight arc and the peak flexion angles of the hindlimb joints. They also calculated the net positive and negative work performed across each joint during the swing phase of movement.

Research Findings

• The speed and stride duration remained the same regardless of whether the horses had the stimulators on. However, the presence of the stimulators reduced the hind stance duration, implying a faster response time.
• The tactile stimulators resulted in a higher flight arc, caused by increased flexions of the stifle, tarsal, metatarsophalangeal (connecting metatarsal bones to the proximal phalanges), and distal interphalangeal (joint between the second and third phalanges) joints.
• While positive work increased in the tarsal (ankle) muscles, there wasn’t a similar increase in the hip muscles. Negative work increased across the stifle, metatarsophalangeal, and distal interphalangeal joints.

Conclusions and Implications

• The findings suggest that tactile stimulation of the hind pasterns affect joint motion and muscle activation. These insights can be useful in physiotherapy and rehabilitation to restore or increase the flexion of the hindlimb joints. However, they found it doesn’t apply to the hip joint.
• The ability to stimulate concentric activity of the tarsal muscles could have therapeutic benefits in conditions such as toe dragging, a common problem in horses where they wear down the toe of the shoe or hoof due to not lifting their feet high enough off the ground.