While many veterinarians have long suspected that infected joints from which bacteria can be cultured result in a poorer outcome than joints from which no bacteria could be cultured, this hypothesis was recently substantiated by a group of United Kingdom researchers led by Tim Mair, BVSc, MRCVS, DEIM, DESTS, Dipl. ECEIM, of the Bell Equine Veterinary Clinic.

Infections of synovial structures such as joints, tendon sheaths, and bursae are both career- and life-threatening events. The hallmarks of an infected joint are heat, pain, effusion, and a rapidly developing and severe lameness.

Common bacterial culprits in joint infections are the enterobacteriaceae (gram-negative bacteria that normally inhabit the intestines, e.g., Salmonella and Escherichia coli), Streptococcus, and Staphylococcus. But for various reasons, bacteria are not always cultured from infected joints.

To determine the influence of synovial fluid culture results on the prognosis for horses treated for infected synovial structures, researchers reviewed medical records from 206 horses treated at the Royal veterinary College Equine Referral Hospital or Bell Equine Veterinary Clinic between 1993 and 2006