More than a quarter of all thoroughbred horses suffer from pulmonary artery calcification, a condition that hardens the main artery connecting the heart and lungs. This condition is linked to premature death in young, athletic horses, which are particularly susceptible to the disease because their bodies attempt to use calcium to reinforce artery walls stretched thin by the increased blood flow experienced while racing. Instaed of helping, the calcium seems to weaken the arteries. Guelph researchers are trying to find out why.
Prof. John Runciman, School of Engineering, and undergraduate students Jeremy Bakker and Matt Teeter are exploring how calcification mechanically affects a horse's arteries. They're working with researchers at the Ontario Veterinary Colleg (OVC) to take a multidisciplinary approach to this complex problem.
"Our portion of the research will hopefully act as the groundwork for understanding the underlying problem of pulmonary artery calcification in horses," says Runciman.
Here's what happens. During arace, thoroughbred horses often run harder than their lungs can naturally handle. Right out of the gate, they experience a four-fold increase in pressure within the arteries of their lungs, including the pulmonary artery. In response to this increase in stress, all of the arteries stretch.
Calcium is part of the natural chemical cocktail response. But calcium's adherence to an arterial wall makes the artery less able to stretch. In addition, the calcium is typically unevenly distributed throughout the arterial wall and forms hard calcium-rich nodules or lesions. These hard spots lead to the overall weakening of the artery.
This phenomenon, called calcification, weakens the artery walls' flexibility and strength. Essentially, calcification increases the stiffness of areas in an artery, and has an overall effect of reducing the artery's ability to stretch, thereby weakening it. This situation can be fatal.
To determine calcium's exact impact on an artery's strength, Runciman's team is modelling inflated pulmonary arteries that are meant to correspond to the stress experienced by the arterial walls when the horse is either at rest, or exercising. They're using these 3-D models to identify areas of high stress on the artery wall.
Runciman's study id part of a larger research project in the Department of Clinical Studies at OVC involving Profs. Luis Arroyo and Laurent Viel. They're looking at the process, cause, origin and development of arterial degeneration in racehorses. It's believed that the mechanical effect that calcification has on the artery wall is an important first step in understanding the impact of arterial calcification on a horse's racing career.
Funding for the reaearch was provided by Equine Guelph.
