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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.

Clinicians and Staff

Mary Rose Paradis

Mary Rose Paradis, DVM, MS, Diplomate ACVIM(LAIM)

Mary Rose Paradis is a 1978 graduate of the School of Veterinary Medicine at the University of Georgia.  Post-graduation, she completed an internship, 1 year of residency and a Master of Science at Washington State University and finished a second year of residency at Michigan State University.  After 2 years of private equine practice on Long Island, NY, she joined the faculty of Tufts University School of Veterinary Medicine at Tufts University in 1983.  She became board Certified in Internal Medicine in 1985.

During Dr. Paradis’ tenure at Tufts University, she has been the course director of the large animal medicine and surgery course for third year students and the large animal medicine clinical rotations for third and fourth year students.  One of her clinical accomplishments includes the establishment of the Marilyn Simpson Neonatal Intensive Care Program.

Dr. Paradis has trained 22 residents and 19 interns in large animal internal medicine. She has acted as faculty mentor and thesis advisor for 10 NIH Research veterinary students and 14 Dorothy Havemeyer Post-Doctoral Fellows.  She received the Norton Teaching Award and was inducted into the inaugural class of the Faculty Hall of Fame by alumni of the Cummings School of Veterinary Medicine at Tufts University as someone that contributed substantially to their education.

Most of Dr. Paradis’ research has been centered on clinical studies of the horse at the 2 extremes of age – the neonate and the geriatric horse.  She is the author or co-author of 41 peer-reviewed papers and 34 book chapters.  She had the privilege of being the editor of a text book published in winter of 2006  – Equine Neonatal Medicine – A Case Based Approach.

Topics of Discussion

Septic arthritis/osteomyelitis is a manifestation of septicemia (widespread infection) in foals.  Approximately one-fourth of foals presented to Tufts Hospital for Large Animals with a suspicion of sepsis also present with or develop evidence of septic arthritis. Cohen and colleagues recognize infectious arthritis as a cause of death in 12.5% of foals (8-31 days of age) in Texas. The problem arises from hematogenous (through the bloodstream) seeding of the synovium (joint lining) and the physis/epiphysis (actively growing bones in the joints) with bacteria. Foals may present with one or multiple joints affected.

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Clinical Case Review

Septic arthritis and osteomyelitis in a neonatal foal
Mary Rose Paradis, DVM, MS, Diplomate ACVIM(LAIM)

’11 Royal Reign, a 10-day old crossbred filly was referred to the internal medicine service at Tufts Cummings School of Veterinary Medicine, Hospital for Large Animals, with a one day history of sudden hind limb lameness. On her physical examination, the filly was bright and alert but had a rapid heart rate of 120 beats/minute and a fever of 103.5. She exhibited left hind limb lameness at the walk; however, no joint or limb swelling was noted. Physical examination of the left hip and sacroiliac (lower back) region elicited a painful response. The filly’s initial blood work was within normal limits with the exception of a low IgG (antibody level) of 400 mg/dl, indicating that she had not had sufficient transfer of antibodies from her dam.

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