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.
Regional Limb Perfusion
Regional Limb Perfusion (RLP)
Regional limb perfusion (RLP) is a technique which provides a high concentration of an antibiotic to the soft tissues, joints, and bones of the limbs. The antibiotic used would be very expensive if given at a dose appropriate for the entire horse but the cost of the drug is more affordable since it is delivered into a superficial leg vein below the level of a tourniquet, and the benefits great. Drug concentrations achieved generally exceed that required to kill many types of bacteria and persist locally in the tissues for an extended period of time. This makes RLP a practical adjunctive treatment for septic conditions affecting the extremities (the knee and hock and below). Continue reading
Techniques of non-invasive Lung Function Testing
In the clinical setting, three main non-invasive methods are currently used at Tufts to test lung function in awake large animals: Forced Oscillation Techniques (FOT), plethysmography and measurement of functional residual capacity (FRC), which is an estimate of lung elasticity.
Forced oscillation techniques (FOT) are non-invasive tests to measure the resistance of the breathing system and thus evaluate airway narrowing. Different frequencies (1-7 Hz) of small air-pulses are directed into the patient’s airways via a face mask, while a computer captures changes in pressure and flow of these waves during spontaneous breathing. This calculates respiratory system resistance (Rrs).
A horse with airway inflammation undergoing FOT lung function testing at Tufts' Hospital for Large Animals.
A high Rrs often indicates airway narrowing due to thickening of bronchial walls and / or mucous accumulation in the lower lung. In horses with lower airway inflammation (e.g. IAD), we commonly observe a frequency dependence of resistance. This means that higher values for resistance are recorded at the lower oscillatory frequencies (1-2 Hz), a finding that is indicative of bronchoconstriction. Higher oscillation frequencies (> 2 Hz) provide information concerning central airway resistance. Baseline respiratory resistance measurements using Forced Oscillation Techniques can also be combined with bronchoprovocation tests to determine airway hyperreactivity or “twitchiness.” Continue reading
Achieving Excellence in Equine Podiatry
Equine podiatry requires collaboration between farriers and veterinarians, says Tufts' Dr. Carl Kirker-Head
If there’s ever a disease that requires the veterinarian’s medical and surgical expertise and the farrier’s anatomical and functional knowledge of the hoof for a successful outcome, it is laminitis. In years past, the two professions often worked in a vacuum, neither one fully engaging the other in the interest of the patient. That situation is now very different, in no small way due to the sustained efforts of a few dedicated educators and practitioners from both professions, along with the gentle encouragement of academic institutions like Tufts University‘s Cummings School of Veterinary Medicine.
Since the early 1990’s Dr. Kirker-Head and the Hospital for Large Animals have hosted annual continuing education podiatry forums, frequently in conjunction with the Southern New England Farriers Association. The subject matter is always interesting. Tufts can lay claim to the only comprehensive forum addressing the farriery needs of the draft horse (2004). Most recently (2010), Dr. Ric Redden – a recognized leader in evolving podiatry techniques for managing laminitis – presented a day seminar on shoeing modalities for problem cases. And like any entity exploring the boundaries of knowledge, one should expect topics to sometimes be controversial Continue reading