Evaluation of digital and laminar blood flow in horses given a low dose of endotoxin.

OBJECTIVE

To measure blood flow in the palmar digital artery and laminae corium, using ultrasonic and laser Doppler flowmetry, respectively.

ANIMALS

6 healthy horses.

PROCEDURE

Digital blood flow and laminar perfusion, respectively, were measured by placing a flow probe around the palmar digital artery and a laser Doppler flow probe in a hole in the dorsal aspect of the hoof wall. All horses were given saline (0.9% NaCl) solution (1 L, IV, during a 30-minute period). Seven days later, each horse was given endotoxin (0.1 microgram/kg of body weight, IV, in 1 L of saline solution, during a 30-minute period). Digital blood flow, laminar perfusion, heart and respiratory rates, body temperature, and clinical signs of endotoxemia were recorded throughout a 240-minute period. Repeated-measures ANCOVA was used to evaluate changes in outcome variables.

RESULTS

Treatment with saline solution did not cause a change in measured variables. All horses had mild clinical signs of endotoxemia. Endotoxin treatment caused a significant decrease in digital blood flow and increases in heart rate and body temperature. Laminar perfusion decreased after endotoxin treatment.

CONCLUSIONS

Endotoxin administration caused a profound transient decrease in digital blood flow and a less substantial decrease in laminar perfusion.

CLINICAL RELEVANCE

Horses with clinical endotoxemia were likely to have decreased digital blood flow and possibly, decreased laminar perfusion, potentially predisposing them to vascular alterations within the digits.