Synovial fluid and plasma concentrations of ceftiofur after regional intravenous perfusion in the horse.

The research investigates the concentrations of the antibiotic ceftiofur in horse joints and blood after administering it regionally in a vein (RIP) or directly into the blood system (IV). The aim is to determine if RIP can be used to increase the concentration of ceftiofur in the joints, thus helping treat infections in horse joints more effectively.

Introduction and Method

• The researchers carried out an experimental cross-over study using five normal adult horses.
• To ascertain the concentration of ceftiofur, an antibiotic, in the synovial fluid of the horse’s joint, two administration methods were compared: regional intravenous perfusion (RIP) and systemic intravenous (IV) administration.
• In each horse, one RC joint (at the knee) was chosen randomly for RIP, while the opposite side was sampled to measure ceftiofur concentrations after IV administration.

Procedure and Analysis

• The researchers introduced an intraarticular catheter (a thin tube inserted into a joint) for ceftiofur administration while the horses were under general anesthesia. A tourniquet was applied in the RIP procedure and ceftiofur (2 g) was administered.
• Blood and synovial fluid were collected over a 24-hour period for analysis using high-performance liquid chromatography equipped with ultraviolet detection.
• The results were interpreted via a linear mixed effect model, a statistical technique used to analyze data collected from different individuals under the same experimental conditions.

Results and Interpretation

• The average concentration of ceftiofur in synovial fluid was found to be higher after RIP than IV administration and remained at a significant level to inhibit common pathogens for over 24 hours.
• The peak concentration of ceftiofur in the synovial fluid after RIP was over 140 times greater than the peak concentration after IV administration.
• Large variations in ceftiofur concentrations in both blood and synovial fluid were observed among different horses, regardless of administration method. However, no adverse effects were reported from either technique.

Conclusions

• The results suggest that regional intravenous perfusion of ceftiofur achieves significantly higher and more prolonged ceftiofur concentrations inside horse joints compared to intravenous administration.
• Additionally, ceftiofur levels remained above the minimum inhibitory concentration (MIC) – necessary to inhibit the growth of common pathogens – for over 24 hours with the RIP technique.
• As such, the researchers suggest that using high doses of ceftiofur through RIP could be a beneficial supplement when treating horse joint infections caused by microbes susceptible to the antibiotic ceftiofur.