Innovation

THE USE OF COMPUTED TOMOGRAPHY IN THE DIAGNOSIS OF SEPTIC ARTHRITIS/OSTEOMYELITIS IN THE NEONATAL FOAL
Mary Rose Paradis*, Mauricio Solano*, Amy Tidwellᵠ , Louise MarandaŦ; *Cummings School of Veterinary Medicine at Tufts University, N. Grafton, MA, ᵠ Private practice;Ŧ UMass Medical School, Worcester, MA

Septic arthritis/osteomyelitis is a recognized sequela to bacteremia (bacteria in the bloodstream) in the neonatal foal. It manifests as lameness with increased joint effusion. Historically, a diagnosis of osteomyelitis is made by radiographic examination of the suspected joint or growth plate, but radiographic evidence of osteomyelitis often lags behind the clinical signs. The hypothesis of this study was that computer tomography (CT) would detect bone lesions earlier and more reliably than radiography in the neonatal foal. Twenty foals between the ages of 8 hours to 36 days were presented to the hospital with lameness secondary to septic arthritis/osteomyelitis during the foaling seasons of 2002 -2006. Clinical information was collected for each foal. A total of 54 joints (34 clinically affected and 20 normal) were evaluated by radiographs and CT.  Foals enrolled in the study had radiographs and CT of the affected joint and contralateral normal joint within 5 days of each procedure (mean =1 day). The images were evaluated by 2 board certified radiologists (individually and blinded) for the presence of osteomyelitis. Descriptions of the lesions were noted. It was found that investigators were more likely to agree on the presence of osteomyelitis from CT on normal and abnormal joints (Kappa 1 and 0.86 respectively) than normal and abnormal radiographs (Kappa 0.714 and 0.476.). CT was 1.7 times more likely to detect osteomyelitis than radiography. Our conclusion was that osteomyelitis lesions in foals with septic arthritis are more likely to be seen earlier with the use of CT than radiographs. This could have an effect on both the treatment choices and prognosis for affected foals.