Aortic-iliac thrombosis in horses.

The research seems to focus on clinically diagnosing vascular obstruction in the hindlimbs of 15 identified horses. In a few cases, post-mortem necropsies revealed this condition along with the oldest lesions located around aortic quadrifurcation and other areas, which consisted partially or completely obstructive masses of fibrous tissue. The cause of these lesions remains uncertain, and may result from strongyle-related thromboemboli or expanding fibrous intimal plaques. Hypercoagulability of the blood could also be a contributing factor.

Overview

This research focuses on examining and diagnosing hindlimb vascular obstruction in horses. The researchers studied 15 clinically diagnosed horses, then performed necropsies on eight of these. Additionally, in two other instances, this condition was a spontaneous post-mortem finding.

Clinical signs

• The primary symptoms in the affected horses included hind-leg lameness and increasing exercise intolerance.

Post-mortem findings

• Post-mortem examination revealed obstructive masses in certain arteries, consisting of well-organized and well-vascularized fibrous tissue. These occlusions were occasionally found to contain hemorrhagic or degenerate areas.
• Larger, unorganized thrombi were often found proximal to the smaller, well-organized masses.
• In the areas surrounding these obstructive masses, the tunica intima layer of the artery was often eradicated, except for the internal elastic lamina, which typically remained intact. The tunica media layer was generally spared, except for instances of ischemic necrosis within significantly distended arteries or beneath thick plaques.

Pathogenesis

• The formation of these lesions is still uncertain. They might result from the organization of strongyle-related thromboemboli or may be due to the progressive enlargement and organization of spontaneously developing fibrous intimal plaques.
• In one horse with nephrotic syndrome, hypercoagulability, a condition that increases the risk of blood clots, could have contributed to the thrombosis.

Recommendations

• The researchers recommend regular inspection of the horses’ aortic quadrifurcation and primary branches. This will enhance early detection of sub-clinical changes and improve understanding of the progression and nature of these lesions.