Equine endotoxemia: pathomorphological aspects of endotoxin-induced damage in equine mesenteric arteries.

This research investigates the effects of endotoxin on the morphology of horse mesenteric arteries, finding that the endotoxin can cause vasoconstriction that may lead to gastrointestinal dysfunction such as stoppage of intestinal peristalsis.

Objective of the Study and Methodology

• The study aimed to evaluate the effects of endotoxin on the morphology of equine mesenteric arteries – the blood vessels that supply the intestinal tract of horses.
• The researchers tested on two thoroughbred horses, administering two intravenous injections of a sublethal dose of endotoxin, 24 hours apart.

Findings From the Experimental Administration of Endotoxin

• Each dose of endotoxin produced symptoms similar to clinical cases of equine colic with a bowel obstruction attribute. These include diarrhoea within 2 hours after the injections, followed by a stop to both faecal excretion and sounds of intestinal peristalsis, the latter being the wave-like contractions and relaxations of the gut that move food along.
• The most notable morphological change observed in the horses was the moniliform appearance (characterized by contracted and dilated segments) of their small mesenteric arteries.
• Other manifestations included the thickening of the artery walls (parietal hyalinization) and both intramural and extramural haemorrhages (bleeding within and outside the walls of the artery).

Implications of the Findings

• The alterations in the horses’ mesenteric arteries might indicate temporary constrictions in the blood vessels (vasoconstriction), which led to decreased blood flow to the mesentery and intestines.
• This diminished blood supply could impact gastrointestinal functions, potentially causing a pause in the operation of intestinal peristalsis – the mechanism that moves food along the digestive tract.
• This conclusion provides valuable insight into the potential physical impacts of endotoxemia in horses, particularly in understanding the effect of endotoxins on intestinal blood flow and function.