John Runciman PhD PEng

 

Investigators:       J Runciman

                            L Arroyo, OVC - Department Clinical Studies

                            L. Viel, OVC - Department of Clinical Studies

                            A. Valverde, OVC - Department of Clinical Studies

 

Students:  M Teeter, J Bakker, L Patrick& I Whatley

Approximately 80% of racehorses can be expected to develop Exercise-Induced Pulmonary Haemorrhage (EIPH) during their career. The management and treatment of EIPH have a substantial economic impact to the equine industry, with the cost of treating EIPH estimated to exceed $100 million annually in the United States alone.

There is currently a poor understanding regarding the cause of EIPH and potential mechanisms include capillary stress failure, pulmonary fibrosis, and small airway disease.  Currently, the most accepted cause for EIPH is exercise-induced pulmonary hypertension, resulting in pulmonary capillary rupture.

Recently we observed the presence of calcification and fibrosis of the pulmonary artery wall in a large proportion of racehorses. Such lesions are known to interfere with elasticity that the vessel needs in order to accommodate the cardiovascular pumping action of the heart during strenuous exercise.  Indeed, arterial calcification is the most important cause of vascular stiffness in humans and is considered a predictive factor for cardiovascular mortality, coronary morbidity and fatal stroke. 

Similarly, we suspect that the compliance of the pulmonary arterial wall of horses with artery calcification is affected.  This impaired compliance will directly affect the capacity of the vessel to deal with large fluctuations in blood pressure, which may in turn cause the downstream microvasculature damage seen with EIPH.

We hypothesize that the pulmonary artery compliance of horses with calcified arteries is impaired. Our research previous research examined the relationship between pulmonary vessel loading and calcification. Our current study is examining pulmonary artery relative stiffness and its impact on blood flow characteristics.         

Equine Cardiovascular Research

A horse suffering from Exercise Induced Pulmonary Haemorrhage (EIPH).