Denervating the pelvic suspensory ligaments of horses causes morphological and histological changes in the ligaments.

The research aims to examine the changes in pelvic suspensory ligaments of horses after they are denervated, with a particular focus on the effects of chronic inflammation on these changes. The study indicates that denervation can lead to decreased muscle size and histological abnormalities signaling neurogenic atrophy, possibly increasing the ligament’s risk of injury.

Research Methodology

• The researchers used ten horses for this study.
• In 5 of these horses, one randomly selected pelvic suspensory ligament (SL) was injected with collagenase to instigate desmitis, an inflammation of ligamentous structures. 42 days later, the proximal part of both pelvic SLs in these horses were denervated.
• After 120 days of being denervated, the morphological and histological characteristics of each collagenase-injected, denervated SL were compared with the corresponding ligament from the other leg which was denervated but not inflammation-induced. Both were also compared to the non-denervated pelvic SLs from the remaining 5 horses, chosen for their similarity in weight and age.

Findings

• The average width and cross-sectional area of the musculature in all denervated SLs were significantly smaller than those of the non-denervated ligaments.
• The mean thickness of collagenase-injected denervated ligaments, but not that of the non-injected denervated ligaments, was notably less than that of the non-denervated ligaments.
• Every denervated ligament presented with histological abnormalities typical of neurogenic muscle atrophy.

Conclusions

• Denervation, or loss of motor neuronal input, to the proximal part of the pelvic limb SLs in horses causes neurogenic atrophy of the musculature in that part of the ligament.
• Such denervation could potentially weaken the ligament, thereby increasing the risk of injury.
• If a SL experiences chronic inflammation before denervation, it may aggravate the muscular atrophy following denervation.