Evidence supporting exercise-induced pulmonary haemorrhage in racing greyhounds

Abstract

Exercise-induced pulmonary haemorrhage (EIPH) is a major health concern in performance horses, but the presence and severity of this condition in racing greyhounds has received little attention. While equids and greyhounds share many physiological attributes, there are important structural and functional differences that may help protect greyhounds from EIPH. We tested the hypothesis that greyhounds performing a simulated 503 m race would experience EIPH and that the time course of recovery would be similar to the horse, even though the severity or relative extent as indexed by the concentration of red blood cells [RBCs] in bronchoalveolar lavage (BAL) fluid would be lower in comparison with that demonstrated previously in horses. Greyhound dogs (n ¼ 6) raced on two occasions (separated by 7 weeks) and BAL was performed 1 week before, 2 h after and each week for 4 weeks following each race to examine the [RBC], concentration of white blood cells [WBCs], WBC differentials and haemosiderophages in the lungs. Racing increased 10 min post-exercise venous blood [lactate] to 18.6^0.4 mmol l 21 . No epistaxis or pink froth was observed at the nose or mouth of any of the dogs. The [RBC] in the BAL fluid was increased significantly 2 h post-race (baseline ¼ 109.6^11.7 £ 10 3 ; post-race ¼ 292.3^69.9 £ 10 3 RBC ml 21 BAL fluid, P , 0.05) and returned to baseline 1 week post-race (149.2^46.2 £ 10 3 RBC ml 21 BAL fluid, P . 0.05 versus baseline). The number of haemosiderophages was not different for any of the measurement periods. The [WBC] in the BAL fluid decreased from baseline and race values at 2, 3 and 4 weeks post-exercise (all P , 0.05). Alveolar neutrophil concentrations were also decreased from baseline and immediate post-race values for 4 weeks post-race. The increased [RBC] in the BAL fluid post-exercise is consistent with the presence of EIPH in these greyhounds. However, the relative extent of EIPH in greyhounds (as indexed by [RBC] in the BAL fluid), as compared with that in the horse, was mild, and the lack of elevation of WBC suggests that, unlike their equine counterparts, inflammatory airway disease was absent.

Distribution of venous remodeling in exercise-induced pulmonary hemorrhage of horses follows reported blood flow distribution in the equine lung

“…Although EIPH has been documented in a variety of species, including humans, dogs, and camels, it is most common in horses. (1,4,8,9,11,15,31,40). In racing Thoroughbreds, where the prevalence of EIPH approaches 80%, it is associated with impaired performance (12).…”

Lung region and racing affect mechanical properties of equine pulmonary microvasculature

“…exercise-induced pulmonary hemorrhage; venous remodeling; lung region; vessel wall mechanics EXERCISE-INDUCED PULMONARY hemorrhage (EIPH) is defined as the presence of frank blood (of pulmonary origin) in the airways after a bout of intense exercise (28,30,32). The condition has been reported in several athletic species, including humans (12), racing dogs (10), and camels (1); however, it is most commonly described in horses (6,32). The incidence rate of EIPH in racehorses exceeds 75% (6,34) when diagnosed by tracheo-bronchoendoscopic examination within 30 -90 min of exercise (16).…”

Relationship between tracheobronchoscopic score and bronchoalveolar lavage red blood cell numbers in the diagnosis of exercise‐induced pulmonary hemorrhage in horses

“…Although TBE assigns 1 of 5 possible scores (0‐4) as a reflection of EIPH severity, evaluation by BAL is semi‐quantitative and has been used to assess the severity of EIPH in horses, cyclists, and greyhounds . Distal segments of a lung are lavaged after exercise, as much lavage fluid as possible recovered, and the number of RBC in that fluid (BALFRBC) determined.…”