Microvasculature of the suspensory ligament of the equine hind limb.

This research describes the microvascular structure of the hind limb suspensory ligament in horses, identifying that this ligament has a uniformly distributed and abundant microvascular supply. The researchers found no indication of deficient vascular supply, suggesting a lack of vascular supply isn’t accountable for the high rate of related injuries or lameness.

Research Methodology

• The study utilised 18 hind limbs taken from 9 adult horses. These horses were euthanized due to reasons not related to lameness.
• A catheter was placed in the transected cranial tibial artery at the level of the mid-distal tibia of each hind limb.
• For two limbs, 120 to 150 mL of a contrast medium was injected to identify the main vasculature using contrast-enhanced Computed Tomography (CT). For the remaining 11 limbs, India ink was injected to identify microvasculature using the Spalteholz tissue-clearing technique.
• Histological evaluation was carried out on transverse sections from 4 out of the 18 hind limbs for further examination.

Research Findings

• The hind limb suspensory ligament is primarily supplied by branches of the medial and lateral plantar metatarsal arteries. The medial and lateral plantar arteries and their associated proximal and distal deep plantar arches also supply it to a lesser degree.
• A consistent intraligamentous microvascular supply was observed, with no relative deficiencies in vascularity found amongst the proximal, midbody, and distal regions of the ligament.
• A network of connective tissue was seen entering and surrounding the suspensory ligament, which included cross-sections of the principal vasculature’s branches. These histological observations corroborate the earlier findings regarding the microvascular supply.

Research Conclusions

• The study concluded that the equine hind limb suspensory ligament has a uniformly distributed and abundant microvascular supply throughout its length, and no evidence suggested any relative deficiency of this vascular supply.
• The findings suggest that hypovascularity, or reduced blood flow, doesn’t seem to be a plausible explanation for the frequent occurrence of injury and resultant lameness related to the proximal hind suspensory ligament in horses.