How risky is medicating joints?

Injecting medication directly into the joint is a common procedure for treating injuries in competition horses. It carries a risk of introducing infection into the joint. However, a recent report suggests that with adequate preparation serious consequences are uncommon.

Lewis Smith and colleagues examined clinical records of all horses given intra-articular injections by nine ambulatory veterinary surgeons over a five year period. The vets were based at a specialist equine practice in Newmarket England dealing mainly with Thoroughbred racehorses. Data relating to intra-articular injections for diagnostic purposes were not included in the study.

The site of injection was prepared using standard aseptic technique, but usually the hair was not clipped.  All injections were made using scrupulous aseptic injection technique.

During the study period, 9456 injections were performed, including corticosteroids (92.3%) antibiotic (amikacin)( 94.8%) and polysulphated glycosaminoglycans (PSGAGs)(0.15%).

Twelve horses developed complications after medication. Four of those developed joint sepsis, but all returned to work after having the joint flushed.

Analysis of the data showed that administration of PSGAGs into the joint, was significantly associated with joint infection. Overall, intrasynovial medications that included amikacin were less likely to develop joint sepsis, but the difference was not significant if the PSGAGs were excluded from the analysis.

The authors concluded that the risk of  sepsis being induced inadvertently following intrasynovial medication was extremely low. They advised that intrasynovial medication with PSGAGs should be  avoided unless antimicrobials are given at the same time.

For more details see:
Risks of synovial sepsis following intrasynovial medication in ambuatory practice, 2006-2011: 9456 intrasynovial injections. Smith, L., Palmer, L., Shepherd, M., Steven, W.N., Dallas, R., Baldwin, G., Sommerville, G., Hawthorne, T. and Ramzan, P.
Equine Veterinary Journal (2013) 45, Suppl. 44, 6  (no11)