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Arterionecrosis of the equine mesentery in naturally occurring endotoxaemia
M Oikawa1, T Ueno, H Yoshikawa
1Equine Research Institute, Japan Racing Association, 321-4 Tokami, Utsunomiya, Tochigi 320-0856, Japan.
Abstract:
This report describes the mesenteric arteriolar lesions in a Thoroughbred racehorse with endotoxaemia due to colic. The vascular lesions consisted of a striking loss of medial smooth muscle cells, associated with granular cell debris derived from necrosed muscle cells, plasma insudation, erythrocyte infiltration and the deposition of a fibrinoid substance (fibrinoid degeneration) in the entire arterial wall, possibly produced by the infiltration of blood components through endothelial cell junctions into the arterial wall. The morphology of the mesenteric arteriolar necrosis closely resembled that seen in experimental equine endotoxaemia and in horses that died from colic; it also resembled that of Shiga toxin-induced arteriolar lesions in oedema disease of swine and of the arterionecrosis in human cerebral arteries that may lead to hypertensive intracerebral haemorrhage.
Insights
Mesenteric arteriolar lesions in a Thoroughbred racehorse with endotoxaemia (a condition caused by bacterial toxins) were observed. These vascular changes, including smooth muscle cell loss and fibrinoid degeneration, resemble those in experimental equine endotoxaemia and other species.
Area of Science:
- Veterinary Pathology
- Equine Medicine
- Toxicology
Background:
- Colic is a common gastrointestinal disorder in horses, often associated with endotoxaemia.
- Endotoxaemia can lead to systemic inflammatory responses and vascular damage.
- Understanding specific vascular lesions is crucial for diagnosing and managing severe equine conditions.
Observation:
- A Thoroughbred racehorse experiencing endotoxaemia secondary to colic presented with distinct mesenteric arteriolar lesions.
- Microscopic examination revealed significant loss of medial smooth muscle cells.
- The arterial walls showed plasma insudation, erythrocyte infiltration, and fibrinoid degeneration.
Findings:
- The observed mesenteric arteriolar necrosis was characterized by cellular debris from necrosed muscle cells and fibrinoid substance deposition throughout the arterial wall.
- These vascular changes are hypothesized to result from plasma component infiltration through endothelial junctions.
- The morphological features closely mimicked lesions found in experimentally induced equine endotoxaemia and naturally occurring cases of colic.
Implications:
- The findings provide a detailed morphological description of vascular damage in equine endotoxaemia.
- The resemblance to lesions in swine oedema disease and human hypertensive intracerebral haemorrhage suggests conserved pathological mechanisms.
- This research aids in understanding the pathogenesis of colic-associated vascular complications in horses.
