Acute thrombosis of limb arteries in horses with sepsis: five cases (1988-1998).

The presented research paper discusses the occurrence and potential causes of acute thrombosis in the limb arteries of horses suffering from sepsis, drawing data from five cases that examined between 1988 and 1998.

Research Context and Methodology

• The study scrutinizes incidences of thrombosis, a serious condition that involves blood clots forming in the arteries of the limbs, in horses under septic or endotoxaemic shock. This is a state in which bacteria infiltrate the bloodstream, and a typical symptom is poor blood flow to the extremities of the body.
• The research spans both neonatal foals and older horses, aiming to establish patterns or correlations between sepsis and the onset of thrombosis. Neonatal foals displayed occurrences of thrombosis typically when affected by gram-negative bacteria.
• For older horses, correlates included inflammatory bowel disease, diarrhoea and toxaemia, further suggesting potential links between infection and thrombosis.

Treatment and Diagnostic Indicators

• All the horses studied had been treated with broad-spectrum antibiotics, nonsteroidal anti-inflammatory drugs, and administered with intravenous (i.v.) crystalloid solutions.
• In addition, two horses were treated with i.v. hyperimmune plasma – a type of treatment that bolsters the immune system.
• Interestingly, prior to the horses showing clinical signs of distal limb necrosis, a generalised coagulopathy – a condition that disrupts the blood’s ability to coagulate – wasn’t suspected. However, in four of the five cases, thrombocytopenia – a deficiency of platelets in the blood – occurred either at the time of, or shortly before, the onset of thrombosis.

Possible Causes and Risk Factors

• The researchers propose that thrombocytopenia may have caused the thrombosis, as platelets adhering to exposed subendothelial collagen can activate the intrinsic coagulation pathway. This phenomenon has been previously reported in horses and foals impacted by gastrointestinal infectious or inflammatory diseases, and disseminated intravascular coagulation (a condition that causes small blood clots to develop throughout the bloodstream).
• The activation of procoagulants by endotoxins, a reduced blood flow to the limbs, and damage to the endothelium (interior lining) of blood vessels, could have collectively created a hypercoagulable condition, eventually leading to thrombosis in the five clinical cases reviewed.
• The research suggests that horses with enterocolitis – inflammation of the small intestine and colon – may have an increased risk of thrombosis. This could be due to the loss of antithrombin III (a protein that prevents blood clots), haemoconcentration (increasing concentration of cells and solids in the blood), and acidosis (a process causing increased acidity in the blood and other body tissues).