One approach to dangerous joint infections in the horse involves isolating treatment to the infected limb, a procedure that can be performed while the horse is standing and awake or "sleeping" under general anesthesia. So which is best? A group of researchers in South Africa recently sought to answer this question, and Arnold T. Mahne, BVSc, of the University of Pretoria, in Onderstepoort, South Africa, presented the results at the 2011 American Association of Equine Practitioners convention, held Nov. 18-22 in San Antonio, Texas.
Mahne described the study in which he and colleagues conducted "intravenous regional limb perfusion" in horses that were either under general anesthesia or that remained standing, measuring both discomfort caused by the procedure and efficacy.
Intravenous regional limb perfusion (IRLP) involves injecting one or more antibiotics into a vein that supplies blood to the lower limb by isolating it with a tourniquet. This procedure provides very high concentrations of medications to the lower limb, which is difficult to achieve using standard routes of antibiotic administration (i.e., oral, intramuscular, or intravenous [IV]).
Sometimes veterinarians perform IRLP with the horse under general anesthesia (GA) and other times they complete it in the standing, sedated horse, with or without a "nerve block" or other local anesthesia to minimize pain and discomfort. Putting a horse under general anesthesia is expensive and is typically a risky procedure due to, among other factors, the amount of stress it puts on the animal.
To determine which technique was the most comfortable and effective in horses, Mahne and colleagues looked at pain levels (by monitoring changes in heart and respiratory rate, the number times the horse lifted the targeted leg, and a visual analog scale of discomfort) and measured amikacin (antibiotic) levels in the knee joint. Horses were divided into four groups: GA; standing sedation alone; standing sedation plus nerve block; and standing sedation plus IV anesthesia (local anesthetic drug was injected IV in the lower limb).
The researchers found:
- No significant difference in amikacin (antibiotic) levels among the groups of horses. All treatments resulted in therapeutic levels of amikacin;
- Horses were more comfortable in the standing sedation plus nerve block group than in both the standing sedation alone and standing sedation plus IV anesthesia groups; and
- Horses in the standing sedation plus nerve block group lifted their legs fewer times than horses in the standing sedation alone group.
"Based on this study GA for IRLP is not justified as this procedure can safely, effectively, and comfortably be performed (with the horse) standing, particularly when done with a nerve block," concluded Mahne.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.