Relationship of pulmonary arterial pressure to pulmonary haemorrhage in exercising horses

Abstract

Summary Exercise‐induced pulmonary haemorrhage (EIPH) is characterised by blood in the airways after strenuous exercise and results from stress failure of the pulmonary capillaries. The purpose of this experiment was to establish a threshold value of transmural pulmonary arterial pressure at which haemorrhage occurs in the exercising horse. Five geldings, age 4–14 years, were run in random order once every 2 weeks at 1 of 4 speeds (9, 11, 13, 15 m/s); one day with no run was used as a control. Heart rate, pulmonary arterial pressure and oesophageal pressure were recorded for the duration of the run. Transmural pulmonary arterial pressure was estimated by electronic subtraction of the oesophageal pressure from the intravascular pulmonary arterial pressure. Within 1 h of the run, bronchoalveolar lavage was performed and the red and white blood cells in the fluld were quantified. Red cell counts in the lavage fluid from horses running at 9, 11 and 13 m/s were not significantly different from the control value, but after runs at 15 m/s, red cell counts were significantly (P<0.05) higher. White cell counts were not different from control values at any speed. Analysis of red cell count vs. transmural pulmonary arterial pressure indicated that haemorrhage occurs at approximately 95 mmHg. Red cell lysis in the lavage fluid was also apparent at transmural pulmonary arterial pressures above 90 mmHg. We conclude that, in the exercising horse, a pulmonary arterial pressure threshold exists above which haemorrhage occurs, and that pressure is often exceeded during high speed sprint exercise.

Using eye temperature and heart rate for stress assessment in young horses competing in jumping competitions and its possible influence on sport performance

“…In fact, despite the fact that most acute stress responses (like the 'flight or fight response') seem to be beneficial and desirable for the animal (as they promote a physical and physiological adaptation to the environment), some naturally rewarding behaviours, such as exercise, can also induce an acute stress response in a very similar profile to that which produces distress (Droste et al, 2003). As regards horses, different studies have reported either negative or positive physical and physiological effects due to an acute stress response during exercise (Langsetmo et al, 2000;Moberg, 2000).…”

Diagnostic Approaches for the Assessment of Equine Chronic Pulmonary Disorders

“…Exercise-induced pulmonary hemorrhage (EIPH) occurs in the majority of racehorses and is observed sporadically in many other sport horses that require strenuous exercise for short periods [14,15]. Proposed pathophysiological mechanisms include high pulmonary vascular pressures during maximal exercise as well as pulmonary inflammation or obstruction of the upper or lower airways [14,16,17]. Other lower airway disorders like granulomatous, neoplastic diseases, or interstitial pneumonias are rarely diagnosed in horses [14].…”

Avaliação endoscópica das vias aéreas, do perfil de gases, dos eletrólitos e do equilíbrio ácido-base em equinos submetidos ao treinamento de três tambores

“…No entanto, neste experimento, foi observada a correlação (r=0,75) entre HPIE e velocidade no grupo TE. Thomas et al (1983) relataram que cavalos PSI de corrida submetidos a exercício intenso apresentam aumento linear do débito cardíaco conforme incremento da velocidade, com aumento da pressão arterial e, consequentemente, em capilares pulmonares (Langsetmo et al, 2000). Os resultados sugerem que os animais do grupo TE não estão adaptados e condicionados ao treinamento, logo não suportariam altas velocidades e consequente aumento da pressão arterial, estando predispostos a falhas nos capilares pulmonares, corroborando a teoria (HPIE) mais aceita entre os pesquisadores.…”