Injecting medication directly into a horse's joint might make some owners wary of complications. But British researchers have recently shown that, when careful aseptic techniques are used, the risks are actually very low.

Synovial sepsis—infection of the intra-joint (synovial) area—following therapeutic injection is “extremely low” when the veterinarian uses aseptic techniques, said Lewis C.R. Smith, BVetMed, CertES(Orth), DipECVS, MRCVS, of Rossdales Equine Hospital in Newmarket, Suffolk, England.

Smith and colleagues reviewed all 9,456 intra-synovial medications (ISMs) administered by nine different veterinarians in the practice over a five-year period (2006-2011). They administered these injections to 1,732 horses—mostly Thoroughbred racehorses—in 4,332 sessions. The most commonly medicated joints were the knee, the front fetlock, and the hind fetlock.

After reviewing the records, the team noted only 12 complications from nearly 9,500 injections—and only four of those actually developed into synovial sepsis. All four synovial sepsis cases were successfully treated with joint lavage, and the horses returned to their regular training and performance routine in two to six months, Smith said