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Evaluation of digital and laminar blood flow in horses given a low dose of endotoxin
1Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State Univesity, Fort Collins 80523, USA.
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.