The effect of herbal supplementation on the severity of exercise-induced pulmonary haemorrhage

Abstract

Exercise-induced pulmonary haemorrhage (EIPH) is a serious condition that affects the health and possibly the performance of all racehorses. However, only two treatments, furosemide and the Flair™ equine nasal strip, both of which reduce capillary transmural pressure, have been successful in reducing EIPH. Alternatively, transient impairment of platelet function and coagulation during exercise has been considered an additional contributor to EIPH. Consequently, herbal formulations designed to enhance platelet function, and hence coagulation, are hypothesized to reduce EIPH. To investigate the validity of this hypothesis, five Thoroughbred horses completed three maximal incremental exercise tests on a 10% inclined treadmill in a randomized cross-over design experiment. Treatments included twice daily oral administration (for 3 days) of a placebo (PL; cornstarch) and two herbal formulas, Yunnan Paiyao (YP) or Single Immortal (SI). Blood samples for coagulation profiles, complete blood counts and biochemistry profiles were collected before each exercise test. During each test, pulmonary arterial pressure, oxygen uptake, arterial blood gases, plasma lactate and time-to-fatigue were measured. Severity of EIPH was quantified via bronchoalveolar lavage (BAL) at 30–60 min post-exercise. The herbal formulations were not effective in decreasing EIPH (×106 red blood cells ml−1 BAL fluid: PL, 27.1±11.6; YP, 33.2±23.4; SI, 35.3±15.4, P>0.05) or in changing any of the other variables measured with the exception of time-to-fatigue, which was slightly but significantly prolonged by Single Immortal compared with placebo and Yunnan Paiyao (PL, 670±9.6 s; YP, 665±5.5 s; SI, 685±7.9 s, P<0.05). Thus, these results do not support the use of these herbal formulations in the prevention of EIPH.

Evidence supporting exercise-induced pulmonary haemorrhage in racing greyhounds

“…Bronchoalveolar lavage (BAL) has been utilized for a little over a decade in horses to evaluate the concentration of RBC present in the BAL fluid post-exercise 51 , and is frequently referred to in the equine 2,3,[17][18][19]22,[45][46][47][48][49] and human literature 7,89 to quantify the degree or severity of EIPH. An advantage of BAL is that there is not a precise window of time within which BAL has to be performed, as is the case with endoscopy 2,90 .…”

“…Even though King et al 8,9 did visualize small amounts of bleeding in two dogs with endoscopy, the relatively low [RBC] in BAL observed post-race in the current study would not likely have been observed with endoscopy 1,2,51,92 . The 2 h post-race lavage was chosen versus 30 min post-race as is conventional in the equine literature 2,3,[17][18][19]22,[45][46][47][48] and similar to the King studies 8,9 due to the increased safety of transporting the dogs back to the veterinary teaching hospital for the procedure instead of anaesthetizing the dogs at the track. The 2 h post-race lavage was chosen versus 30 min post-race as is conventional in the equine literature 2,3,[17][18][19]22,[45][46][47][48] and similar to the King studies 8,9 due to the increased safety of transporting the dogs back to the veterinary teaching hospital for the procedure instead of anaesthetizing the dogs at the track.…”

“…Unpublished radiographic data (TS Epp, AM Buchannan, L Gates, DC Poole and HH Erickson) from our laboratory suggest a similar caudal lung lobe placement (seven out of seven dogs) when a BAL tube is passed blindly (five right caudal lung lobes versus two left caudal lung lobes) in the greyhound. It is also important to keep in mind that the greyhounds utilized in this study were not selected based upon a prior history of severe EIPH, as is often the case in horse studies 3,19,22,23,[45][46][47] . Therefore, it may be of importance that King et al 8,9 showed that the left lung may haemorrhage to a greater degree than the right one, which is in contrast to what has been observed in the horse 2,95 .…”

“…One week after the baseline lavage, the initial post-race lavage was performed c. 2 h post-exercise under general anaesthesia, this sampling procedure examined the number of RBC per millilitre of BAL fluid (which is considered to be a reflection of the amount of blood in the airways post-exercise), which we took as an indirect measure of the relative extent of EIPH 2,3,8,9,[17][18][19]22,23,[45][46][47][48][49] . One week after the baseline lavage, the initial post-race lavage was performed c. 2 h post-exercise under general anaesthesia, this sampling procedure examined the number of RBC per millilitre of BAL fluid (which is considered to be a reflection of the amount of blood in the airways post-exercise), which we took as an indirect measure of the relative extent of EIPH 2,3,8,9,[17][18][19]22,23,[45][46][47][48][49] .…”

Exercise‐induced pulmonary haemorrhage (EIPH): mechanistic bases and therapeutic interventions

“…In addition, there is emerging evidence that haemostatic agents, such as aminocaproic acid and conjugated oestrogens may, via their antifibrinolytic effects (Heidmann et al 2005), also decrease the severity of EIPH (H. H. Erickson and T. S. Epp, unpublished data). In contrast to the above, neither inhaled nitric oxide (irrespective of lowering pulmonary artery pressure, Kindig et al 2001b) nor herbal formulations designed to remedy putative coagulation defects (Epp et al 2005)…”