Development of intraosseous infusion of the distal phalanx to access the foot lamellar circulation in the standing, conscious horse.

This research article presents the development of a new method for delivering drugs directly to the hoof lamellar tissue in conscious horses, using intraosseous infusion into the distal phalanx (IOIDP). The technique was successfully tested in Standardbred horses, demonstrating that the administered drug was present in the target tissue at much higher concentrations than in peripheral serum.

Objective of the study

• The main objective of this study was to develop a safe and effective method for delivering drugs directly to the hoof lamellar tissue of standing, conscious horses through intraosseous infusion into the distal phalanx (IOIDP). This method would allow medications to reach the target tissue in higher concentrations, thereby potentially increasing their effectiveness.

Methodology

• The experiment was conducted on six Standardbred horses that were sedated and subjected to regional nerve blockade.
• A microdialysis (MD) probe was implanted into the hoof lamellar tissue of one forelimb, and a specially designed cannulated bone screw was introduced into the body of the distal phalanx, around 6 cm away from the MD probe.
• Gentamicin solution (25 mg/mL) was infused through the bone screw at a rate of 20 microliters/min for two hours. No tourniquet was applied during the infusion.
• MD and blood samples were collected at regular intervals and analyzed to measure gentamicin concentrations.

Results

• The results showed that gentamicin was found in the lamellar tissue at much higher concentrations than in the peripheral serum. Specifically, the mean concentrations of gentamicin were around 24.4, 20.5, and 4.4 micrograms/mL in the extracellular fluid (ECF) and 0.28, 0.5, and 0.32 micrograms/mL in serum samples collected 60, 120, and 150 minutes after IOIDP was initiated, respectively.

Conclusions

• The study successfully demonstrated a new intraosseous infusion method capable of delivering drugs to the hoof lamellar tissue of horses in an efficacious and safe manner.