Epsilon Archive for Student Projects

Abstract

Thoroughbred racehorses have suffered from exercise-induced haemorrhage for over 300 years. Almost all competing horses develop exercise-induced pulmonary haemorrhage (EIPH) at some point but most horses don’t suffer from reduced competing capacity due to the disease. The cause of the exercise-induced haemorrhage is unknown. The most believed theory today is that EIPH is induced by pulmonary stress failure caused by pressure over 100 mmHg in the pulmonary arteries during exercise. The hypothesis of this study is that EIPH is induced by changes in the body fluid balance and chronic metabolic and physical stress. It has been shown that racehorses suffer from endotoxemia during racing but they are also able to cope with it. The final hypothesis in this study is that due to these earlier causes the horse have problems coping with endotoxemia during race. Endotoxemia activates leucocytes, releases vasoactive and inflammatory mediators including tumour necrosis factor α (TNF-α) and interleukin β (IL-β). It furthermore increases neutrophil migration in the lung and these effects of endotoxins on stressed horses forced to maximal exercise is hypothesised to be the final cause of the bleeding and reduced racing capacity.