Digital blood flow and plasma endothelin concentration in clinically endotoxemic horses.

This research investigates the relationship between the severity of endotoxemia in horses, the blood flow in their digits, and concentrations of endothelin-1 (ET-1) in their plasma. It was found that horses with more severe endotoxemia had decreased digital blood flow, increased ET-1 concentrations, and reduced long-term survival rates.

Methodology

• The study examined 36 adult horses undergoing emergency celiotomy due to primary gastrointestinal tract disease.
• Digital arterial blood flow in the horses was measured using Doppler ultrasonographic technique on the 2nd and 5th days post-surgery.
• Plasma concentrations of ET-1 and endotoxin were determined through hematologic and biochemical analyses.
• The researchers used a scoring system based on nine clinical variables to categorize the horses into two groups (Group A and B). Group B constituted the quartile with the greatest cumulative score, while Group A comprised the remaining three quartiles.
• A follow-up was conducted after 2.5 years through a telephone questionnaire.

Results

• On the second day post-surgery, the median plasma ET-1 concentrations for all horses were found to be 1.4 pg/mL. This reduced to 1.0 pg/mL by the 5th day.
• Additionally, the digital blood flow on the second day was 0.057 mL/min in Group A horses and was slower, at 0.035 mL/min, in Group B horses.
• By the 5th day, the plasma ET-1 concentrations were significantly (73%) higher in Group B horses than in Group A horses.
• After 2.5 years, 30 out of the 36 horses were alive, with Group A horses likely to have survived more. The odds ratio was 25 with a 95% confidence interval falling between 2.4 to 262.
• The study found significant associations between increased digital pulses, hoof wall temperatures, or both and increased digital blood flow (0.14 mL/min on day 2) and increased digital arterial diameter (0.32 cm on day 5).

Conclusions

• The study provided evidence suggesting that horses with more severe endotoxemia had decreased digital blood flow and increased plasma ET-1 concentrations. Such conditions also resulted in decreased long-term survival.
• The findings are crucial for equine healthcare as endotoxemia is closely related to severe equine diseases such as colic and laminitis.
• Furthermore, the research adds to the understanding of the effect of endothelin-1 in pathological conditions, as increased ET-1 concentration in the plasma could suggest severity of endotoxemia in horses.