Effect of different protocols on the mitigation of exercise‐induced pulmonary hemorrhage in horses when administered 24 hours before strenuous exercise

Abstract

Background Public pressure exists in the United States to eliminate race‐day furosemide administration despite its efficacy in decreasing the severity of equine exercise pulmonary hemorrhage (EIPH). No effective alternative prophylaxis strategies have been identified. Objective To investigate alternative protocols to race‐day furosemide that might mitigate EIPH. Animals Seven fit Thoroughbreds with recent EIPH. Methods Double‐blinded placebo‐controlled Latin square crossover using a treadmill followed by a blinded placebo‐controlled crossover study at a racetrack. First, horses exercised supramaximally to fatigue 24 hours after initiating 5 EIPH prophylaxis protocols: 0.5 and 1.0 mg/kg furosemide IV 24 hours pre‐exercise with and without controlled access to water, and 24 hour controlled access to water. Effects were compared to those measured after giving a placebo 24 hours pre‐exercise, and 0.5 mg/kg furosemide IV 4 hours pre‐exercise. Bronchoalveolar lavage (BAL) erythrocyte count was determined 45‐60 minutes postexercise after endoscopy to assign an EIPH score. Data were analyzed using linear mixed effects models. The most promising protocol from the treadmill study was further evaluated in 6 horses using endoscopy and BAL after 1100 m simulated races. Results Intravenous furosemide (0.5 mg/kg) administered 24 hours pre‐exercise combined with controlled access to water decreased the severity of EIPH on the treadmill and at the racetrack. Conclusion and Clinical Importance Administering 0.5 mg/kg furosemide 24 hours pre‐racing combined with controlling water intake may be a strategy to replace race‐day furosemide administration for the management of EIPH. A larger study is indicated to further evaluate whether this protocol significantly mitigates EIPH severity.

Physiologic effects of furosemide in combination with water restriction when administered at 4 and 24 hours prior to high‐intensity treadmill training

“…In the current study, a combination of EIPH scoring and quantitation of RBCs in BAL fluid were used to assess the effects of furosemide administration, when administered at 4‐ and 24‐hr prior to exercise, on attenuating bleeding associated with high‐intensity treadmill exercise. To the best of the authors’ knowledge, there are only two reports describing effects on EIPH when administered 24 hr (which would presumably be a nonrace day) prior to exercise (Bayly et al., 2019; Knych, Vale et al., 2018). Changes in pulmonary pressures, blood parameters, and electrolyte concentrations are also described.…”

“…(2000) reported that although no effect was noted in pulmonary hemodynamics when furosemide was administered 1 hr prior to strenuous exercise, more favorable affects with respect to attenuation of exercise‐induced pulmonary capillary and venous hypertension were noted when furosemide was administered 2, 3, and 4 hr prior to exercise (Magid et al., 2000). More recently, there have been reports suggesting that administration of furosemide 24 hr prior to strenuous exercise combined with controlled water intake may be just as effective in diminishing the effects of strenuous exercise on pressures and hemodynamics (Bayly et al., 2019).…”

Thoroughbred Racehorse Welfare through the Lens of ‘Social License to Operate—With an Emphasis on a U.S. Perspective

“…A recent study by Bayly and colleagues demonstrates that furosemide administered 24 h before racing may be equally as effective as the traditional 4 h pre-race dosage [87]. Based on this evidence, the Kentucky Equine Drug Research Council recently reversed its decision related to the phase out of race-day Lasix for 2-year-olds.…”

Detecting fatigue of sport horses with biomechanical gait features using inertial sensors

“…In general, "fatigue" is a multifaceted and a multidimensional term, thus, lacks a consensus definition across different domains of human and equine studies, such as exercise physiology, cognitive psychology and medical practice [11,12]. In many studies, fatigue indicator was considered as the moment that the horse "cannot maintain the pace on treadmill despite verbal encouragement" [13][14][15][16][17][18][19][20][21][22][23][24]. This indicator can be practical in a treadmill measurement setting accompanied by veterinarians.…”