Joint Care: Provide Support After Wounds, Infection

Viscous and transparent, synovial fluid acts as a biological lubricant within musculoskeletal mechanisms. Penetrating wounds to joints and tendon sheaths cause most infections, though pathogens carried in the bloodstream, as with foals diagnosed with joint ill, have been implicated, as has contamination at the time of intraarticular injection or surgery. Veterinarians refer to infection that sets up in any structure containing synovial fluid, namely joints, tendons, and bursas, as synovial sepsis.

Prompt diagnosis and aggressive treatment minimize damage to septic structures and often prevent career- and life-threatening consequences. To determine if infection is present, bacterial isolation through culture is the best diagnostic tool, yet low sensitivity and long laboratory turnaround time often preclude a definite diagnosis in the face of emergency situations and treatment decisions, which may include joint irrigation and surgery. Because of these limitations, researchers have sought alternative ways to quickly identify the presence of infection.

Austrian researchers recently evaluated the presence of specific biomarkers, called antimicrobial proteins, in synovial fluid as a way to confirm infection.^* These proteins are activated by the immune system in response to a pathogenic challenge, so their existence in the fluid indicates sepsis. According to the researchers, “using enzyme activity as a biomarker of synovial sepsis enables the development of a point-of-care diagnostic test, which would allow veterinarians to perform, analyze, and act on test results stall-side, in a matter of minutes.”

In the study, researchers collected synovial fluid samples from three groups of horses: healthy controls, horses with aseptic synovitis (inflammation without infection), and horses with septic synovitis. Enzyme activity assays were compared with standard synovial fluid parameters and broad-range bacterial DNA extraction.

The researchers found enzyme activities were significantly different between septic synovial samples and aseptic and control samples, leading them to believe that measurement of enzyme activities would allow for reliable, rapid diagnosis of synovial sepsis and immediate therapeutic interventions.

Joint health depends largely on conscientious management of exercise, including frequency and intensity of athletic bouts, and the provision of high-quality nutritional supplements formulated specifically for joint support. While synovial sepsis typically develops from injuries that compromise the joint capsule, it can occur following routine intraarticular injection of hyaluronic acid and corticosteroids, though the incidence of infection is uncommon.^° The prophylactic use of joint supplements in high-performance horses and prospects can delay the need for joint injections, thus postponing any risk associated with invasive procedures.

^*Haralambus, R., A. Florczyk, E.  Sigl, S. Gultekin, C. Vogl, S. Brandt, M. Schierer, C. Gamerith, and F. Jenner. 2021. Detection of synovial sepsis in horses using enzymes as biomarker. Equine Veterinary Journal. In press.

^°Steel, C.M., R.R. Pannirselvam, and G.A. Anderson. 2013. Risk of septic arthritis after intra-articular medication: A study of 16,624 injections in Thoroughbred racehorses. Australian Veterinary Journal 91(7):268-273.