Exercise-induced Pulmonary Hemorrhage In Horses Research Articles

Oxygen consumption, locomotory-respiratory coupling and exercise-induced pulmonary hemorrhage in horses during the Paso Fino gait.

Workload associated with the high frequency Colombian Paso Fino gait has not been evaluated. To determine the oxygen consumption (V̇O2), heart rate (HR), stride frequency: breathing ratio, and hematology associated with the Paso Fino gait, including whether exercise-induced pulmonary hemorrhage (EIPH) occurs. Eleven Paso Fino horses. Prospective cohort study. Horses performed a standardized Paso Fino gait test across a wooden sounding board, simulating competition. V̇O2 and ventilatory parameters (tidal volume [VT]; peak inspiratory and expiratory airflows [PkV̇I, PkV̇E]; respiratory rate [RR], minute ventilation [V̇E]) were measured using a portable ergospirometry facemask. Heart rate was measured using electrocardiograms. Post-exercise lactate, hematocrit, bicarbonate, pH, electrolytes, and biochemistry concentrations were measured. EIPH was assessed via tracheobronchoscopy. Four horses completed a secondary high-intensity gallop to elicit peak V̇O2 for comparative purposes. Median [IQR] mean individual HR during the Paso Fino gait was 190 [178, 201] bpm. Relative V̇O2 measured 49.8 [48.4, 59.5] mL/(kg min; VT = 8.6 [8.0, 10.7] L; RR = 87.1 [75.4, 99.5] bpm; V̇E = 869 [740, 902] L/min; PkV̇I = 33.4 [32.7, 37.2] L/s; PkV̇E = 44.2 [40.3, 46.0] L/s). Horses took 2.8 [2.7, 2.9] strides/second and had a stride frequency: breathing ratio of 2.0 [1.8, 2.3]. Post-exercise blood lactate concentration and hematocrit measured 2.7 mmol/L and 50% respectively. Three horses showed endoscopic evidence of Grade-1 EIPH. The Paso Fino gait V̇O2 and HR equaled 79% V̇O2pk and 91% maximal HR, respectively, based on the high-intensity gallop. The Paso Fino gait represents submaximal exercise based on V̇O2 < V̇O2pk and blood lactate.

Validation of a Rapid Bronchoalveolar Lavage Fluid Colorimetric Evaluation for Assessing the Severity of Exercise-Induced Pulmonary Hemorrhage in Horses in Field Conditions

Diagnosis and assessment of severity of exercise-induced pulmonary hemorrhage (EIPH) relies on postexercise visualization of fresh blood in the airways via tracheobronchoscopic examination (TBE) and/or counting erythrocytes in bronchoalveolar lavage fluid (BALFRBC). Determining the BALFRBC is more sensitive than TBE but its usefulness is hampered by the need to have BALFRBC counted at a laboratory. We explored the feasibility of evaluating the severity of EIPH by using a color chart comprised of five shades of red and matching those colors with the color of BALF immediately following collection. To validate the technique, sets of ten BALF samples with known BALFRBC numbers were created and randomly shown to two groups of 18 observers who independently matched the color of the BALF with one of the shades of red displayed on the screen of a smartphone. Interobserver and intra-observer agreements regarding colors were > 0.9. The utility of the color chart was further validated under field conditions at two barrel racing events where 63 BALF samples were collected from 21 horses and BALF color was graded independently by three observers. The number of BALFRBC in the 63 samples ranged from 25–1,100,000/μL. EIPH was diagnosed in 39 samples based on the detection of color, and all 5 colors were matched multiple times with BALF samples. Overall, the color of the BALF was related to the number of BALFRBC. Colorimetric evaluation of BALF represents a practical and reliable option for rapid postexercise assessment of the presence and severity of EIPH.

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

BackgroundExercise‐induced pulmonary hemorrhage (EIPH) is diagnosed and its severity assessed by post‐exercise tracheobronchoscopy, and enumeration of bronchoalveolar lavage fluid red blood cells (BALFRBC). Minimal information is available regarding the relationship of tracheobronchoscopy score to BALFRBC number.ObjectiveEvaluate the relationship between BALFRBC number and tracheobronchoscopy scores and determine their diagnostic sensitivities.AnimalsNine sedentary horses, 21 fit Thoroughbreds, 129 Barrel Racers.MethodsNormal BALFRBC number and the effect of bronchoalveolar lavage (BAL) on it were evaluated by performing 2 BALs 24 hours apart in sedentary horses. Tracheobronchoscopy followed by BAL was performed 247 times on 150 horses after treadmill, racetrack, or barrel racing exercise. Lastly, a BALFRBC diagnostic threshold number that optimized the geometric mean of the sensitivity and precision (F1‐score) was determined using Bayesian analysis.ResultsNo increase in BALFRBC occurred after the second BAL (mean ± SD, 304 ± 173/μL). Tracheobronchoscopy scores ranged from 0 (n = 112) to 4 (n = 4) and BALFRBC ranged from 102 to 4605268/μL. Spearman correlation between tracheobronchoscopy score and BALFRBC was weak (P < .001; rs = 0.42) with large ranges of BALFRBC associated with each tracheobronchoscopy score. The highest F1‐score occurred for a BALFRBC threshold number = 992/μL. Seventy‐five tracheobronchoscopy scores equaled 0 although BALFRBC number was ≥992/μL. Sensitivity of tracheobronchoscopy for diagnosing EIPH was poor (0.59; 95% confidence intervals [CI], 0.49‐0.68), compared to BALFRBC number ≥992/μL (0.93; 95% CI, 0.88‐0.96).Conclusions and Clinical ImportanceFalse negatives are common with tracheobronchoscopy. Follow‐up determination of BALFRBC may be indicated for tracheobronchoscopy scores = 0 before EIPH can be ruled out.

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

BackgroundPublic 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.ObjectiveTo investigate alternative protocols to race‐day furosemide that might mitigate EIPH.AnimalsSeven fit Thoroughbreds with recent EIPH.MethodsDouble‐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.ResultsIntravenous 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 ImportanceAdministering 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.

Exercise-induced pulmonary haemorrhage in horses – review

Exercise-induced pulmonary haemorrhage is a major cause of poor performance in the equine athlete. It is an important cause of exercise intolerance and results from strenuous exercise and pathophysiological changes in the equine lung and possibly in the airways. Endoscopic surveys of the respiratory tracts of horses after competitive events have shown that many horses experience exercise-induced pulmonary haemorrhage. The reported incidence of exercise-induced pulmonary haemorrhage in different breeds varies between 40–85%. The cause of bleeding in exercising horses has fostered considerable debate over the past three centuries, but currently, the most accepted hypothesis is that the source of haemorrhage is disruption of the pulmonary capillaries during exercise. Furosemide is the medication used most widely for the treatment and prevention of exercise-induced pulmonary haemorrhage. This review provides an update on the aetiology, clinical signs, physiopathology, diagnosis and treatment of exercise-induced pulmonary haemorrhage.

Tracheobronchoscopic assessment of exercise-induced pulmonary hemorrhage in horses

To determine the interobserver variability of assessment of exercise-induced pulmonary hemorrhage (EIPH) during tracheobronchoscopic examination in horses. 747 Thoroughbred racehorses. Procedures-850 tracheobronchoscopic examinations were performed within 2 hours of racing for the horses. Examinations were recorded on videotape, and EIPH and its severity were assessed independently by 3 veterinarians. Concordance was determined by calculation of the Cohen weighted kappa statistic and tabulation of scores assigned by each observer. Weighted kappa statistics ranged from 0.75 to 0.80. In 99.4% of observations, all observers agreed or 2 of 3 agreed and the third differed by < or = 1 grade. Results indicated that interobserver reliability of tracheobronchoscopic assessment of EIPH in Thoroughbred racehorses is high when the examination is conducted by experienced veterinarians. Concordance among investigators is sufficient to justify use of this grading system for further studies and clinical descriptions of EIPH.

Frequency of and risk factors for epistaxis associated with exercise-induced pulmonary hemorrhage in horses: 251,609 race starts (1992-1997).

To determine the frequency of epistaxis during or after racing among racehorses and identify factors associated with development of epistaxis. Retrospective study. 247,564 Thoroughbred and 4,045 Anglo-Arab race starts. Race start information (breed, age, sex, racing distance, and race type) was obtained for Thoroughbred and Anglo-Arab horses racing in Japan Racing Association-sanctioned races between 1992 and 1997. All horses that raced were examined by a veterinarian within 30 minutes of the conclusion of the race; any horse that had blood at the nostrils was examined with an endoscope. If blood was observed in the trachea, epistaxis related to exercise-induced pulmonary hemorrhage (EIPH) was diagnosed. Epistaxis related to EIPH was identified following 369 race starts (0.15%). Frequency of EIPH-related epistaxis was significantly associated with race type, age, distance, and sex. Epistaxis was more common following steeplechase races than following flat races, in older horses than in horses that were 2 years old, following races < or =1,600 m long than following races between 1,601 and 2,000 m long, and in females than in sexually intact males. For horses that had an episode of epistaxis, the recurrence rate was 4.64%. Results suggested that frequency of EIPH-related epistaxis in racehorses is associated with the horse's age and sex, the type of race, and the distance raced. The higher frequency in shorter races suggests that higher intensity exercise of shorter duration may increase the probability of EIPH.

Effects of furosemide on athletic performance and exercise-induced pulmonary hemorrhage in horses

Effects of furosemide on athletic performance and exercise-induced pulmonary hemorrhage in horses

Furosemide attenuates the exercise-induced increase in pulmonary artery wedge pressure in horses

Summary Right atrial (ra), right ventricular (rv), pulmonary artery (pa), and pulmonary artery wedge (paw) pressures were examined, using catheter-mounted micromanometers, in 8 healthy horses at rest and during galloping on a treadmill at belt speeds of 8, 10, and 13 m/s. The in vivo signals from the micromanometers were matched with those from conventional fluid-filled catheter transducers leveled at the scapulohumeral joint. Thirty minutes after completing control exercise measurements, furosemide was administered iv at a dosage of 1 mg/kg of body weight, and resting, as well as exercise, measurements were repeated 4 hours later. Studies also were performed on a separate day, when only postfurosemide resting and exercise data were collected. Prefurosemide and postfurosemide heart rate values for rest (37 ± 2 beats/min, mean ± sem), as well as for exercise (213 ± 5 beats/min at 13 m/s), were similar. Prefurosemide mean ra, pa, and paw pressures were increased significantly (P &lt; 0.05) from resting values of 8 ± 2, 31 ± 2, and 18 ± 2 mm of Hg, respectively, to 44 ± 4,89 ± 5, and 56 ± 4mm of Hg with exercise at 13 m/s. Furosemide administration resulted in marked diuresis, and resting mean ra, pa, and paw pressures decreased significantly (P &lt; 0.05) to 1 ± 1, 27 ± 2, and 11 ± 2 mm of Hg, respectively, 4 hours after furosemide administration. Although pressures increased markedly with exercise (corresponding values being 31 ± 5, 79 ± 6, and 44 ± 4 mm of Hg), these 4-hour postfurosemide exercise values were significantly (P &lt; 0.05) less than those recorded with prefurosemide exertion. Intravascular pulmonary capillary pressure, calculated as the average of mean pa and paw pressures, during prefurosemide exercise (73 ± 5 mm of Hg) significantly (P &lt; 0.05) exceeded that during exercise performed 4 hours after furosemide administration (61 ± 5mm of Hg). Attenuation by furosemide of the exercise-induced increase in pulmonary capillary pressure may have a role in limiting or reducing the extent of exercise-induced pulmonary hemorrhage in horses.

Influence of cyclooxygenase inhibitors on furosemide- induced hemodynamic effects during exercise in horses

SUMMARY Furosemide, which commonly is used as a prophylactic treatment for exercise-induced pulmonary hemorrhage in horses, may mediate hemodynamic changes during exercise by altering prostaglandin metabolism. To determine if furosemide's hemodynamic effects during exercise in horses could be reversed, cyclooxygenase inhibitors were administered with furosemide. Four treatments were administered 4 hours prior to treadmill exercise at 9 and 13 m/s. They included a control treatment (10 ml of 0.9% NaCl solution, iv), furosemide (1 mg/kg of body weight, iv) administered alone, and furosemide in combination with phenylbutazone (4 mg/kg, iv, q 12 h for 2 days) or with flunixin meglumine (1.1 mg/kg, iv, on the day of experiment). Five horses were randomly assigned to complete all treatments. Physiologic variables at rest prior to exercise were not influenced by treatments. Furosemide, administered alone, reduced mean right atrial pressure and mean pulmonary artery pressure during exercise. The combinations of furosemide and flunixin meglumine or furosemide and phenylbutazone, at both levels of exercise intensity, returned mean right atrial pressure and mean pulmonary artery pressure to the value of the control treatment. During rest and exercise, plasma lactate concentration, pcv, heart rate, mean carotid artery pressure, oxygen consumption, carbon dioxide elimination, and cardiac output were not altered by any of the treatments. At 5 minutes after exercise, the administration of furosemide, alone or with phenylbutazone, reduced mean right atrial pressure. Other measured variables were not significantly influenced by treatments during recovery from exercise. These results suggested that cyclooxygenase inhibition partially reverses the decrease in mean right atrial pressure or pulmonary artery pressure induced by furosemide during exercise. Furosemide may mediate some of its physiologic activities in exercising horses through the cyclooxygenase pathway.

Exercise-induced pulmonary hemorrhage in horses with experimentally induced allergic lung disease

Summary The lungs of sensitized horses were exposed to aerosolized ovalbumin. Some horses (n = 4) were given ovalbumin in 1 lung only, whereas in others (n = 7), ovalbumin or vehicle were inoculated in the cranial, ventral, and caudal regions of the caudal lung lobe. Horses were exercised 5 hours after ovalbumin exposure. Immediately before exercise, endoscopy failed to reveal any abnormality. After exercise, endoscopic examination of horses subjected to unilateral ovalbumin exposure revealed extensive blood in airways leading to the exposed lung in all horses. Blood was not observed in the airways leading to the control lung. Mean (± sem) minimum volume of the exposed and control lungs was 9.5 ± 1.5 and 5.5 ± 1.6 L, respectively; this difference was statistically significant (P&lt; 0.05). Bronchoscopy of horses subjected to regional ovalbumin or vehicle exposure and exercise revealed a small amount of blood-tinged fluid in the bronchi serving the regions of the lung inoculated with ovalbumin. Minimum volumes of such regions were not significantly different from one another. However, their minimum volume was significantly (P&lt;0.05) larger than that of vehicle-inoculated regions. Gross and histologic examination confirmed inflammation and hemorrhage in the ovalbumin-exposed, but not the control lungs or lung regions. Thus, exercise can cause blood from an injured region of lung to appear in the larger airways. Regional differences in lung structure and function do not influence the appearance of blood in the airways.

Cytologic and endoscopic findings after intrapulmonary blood inoculation in horses

Summary The bronchial trees of 8 horses were inoculated with citrated autologous blood, and subsequent observations were compared with those from 3 controls. Free blood was observed at the external nares of six of the eight horses after inoculation. Changes in the appearance of the trachea and changes in the cytologic properties of tracheal wash aspirates, stained using a rapid Papanicolaou method, were followed over time. The cell types found after blood inoculation included free red blood cells, erythrophages, and siderophages. Erythrophages were found only in the few days after inoculation while siderophages persisted until at least 4 weeks. Finely stippled early siderophages were distinguished from granular aged siderophages. Direct visual assessment ceased to detect blood after 7 days. Ten percent of the tracheal wash samples contained insufficient cells to permit interpretation. In the 4 weeks after blood inoculation, cytologic evaluation was diagnostic of intrapulmonary blood in 20 out of 21 tracheal washes with sufficient cells for evaluation; that is a false negative rate of 1 in 21. Cytologic interpretation gave 1 false positive diagnosis in 20 tracheal washes in the period up to 4 weeks. This protocol could be modified to study the effects of exercise, drug administration or other variables on the clearance of blood from the pulmonary tree. Comparison of such studies with results from horses with exercise-induced pulmonary hemorrhage (EIPH) may improve our understanding, diagnosis, treatment and monitoring of naturally occurring EIPH in horses.

A preliminary report on studies on equine transit stress

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