Evaluation of regional limb perfusion with erythromycin using the saphenous, cephalic, or palmar digital veins in standing horses.

This research explored how erythromycin, an antibiotic, can be used in regional limb perfusion (RLP) therapy for horses, and whether certain veins used for the procedure lead to better therapeutic results. The findings suggest that using either the saphenous or the cephalic veins could help deliver effective amounts of erythromycin to the lower limb of horses.

About The Study

• The study aimed at evaluating the effectiveness of erythromycin treatments using regional limb perfusion, a therapeutic method that delivers medicine directly to a specific area, on horses’ limbs. The researchers were primarily interested in understanding if using specific veins — the cephalic vein, saphenous vein, or palmar digital vein — would deliver therapeutic levels of the drug to the lower limb.
• Nineteen healthy horses were involved in the study. Through different veins, their limbs were perfused with erythromycin. The researchers collected synovial fluid from the metacarpo/metatarso-phalangeal (MCP/MTP) joint, which is the hock joint located in the lower part of the horse’s leg and is similar to the human ankle. They also collected blood samples from the jugular vein to check the concentration of the drug.

Results and Findings

• When the cephalic vein was used to deliver the erythromycin, the maximum concentration (Cmax) of erythromycin in the MCP joint was 113 mg/L. Administering erythromycin using the saphenous vein led to a Cmax of 38 mg/L in the MTP joint.
• However, when using the palmar digital (PD) vein, erythromycin was not detectable in the MCP/MTP joint for 4 out of 6 horses, implying that the PD vein might not be as effective in delivering the drug to the distal limb.
• The study found that the concentration of erythromycin in the synovial fluid were significantly above the minimum concentration needed to inhibit the growth of Rhodococcus equi, a bacterium that can cause severe pneumonia in foals.

Conclusion

• The research concluded that using either the saphenous or cephalic veins for regional limb perfusion with erythromycin could consistently deliver therapeutic concentrations to the MCP/MTP joint in horses.
• The findings could be useful for veterinary practices, especially in the treatment and prevention of infections caused by Rhodococcus equi in horses.