The effect of Exercise Induced Pulmonary Hemorrhage on some performance indices in Standardbred racehorses: preliminary results

Introduction Exercise-induced pulmonary hemorrhage (EIPH) is an important disease of horses, characterized by bleeding from the pulmonary capillaries during or after exercise. EIPH is mostly identified in racehorses, affecting over 80% of Thoroughbreds and Standardbreds performing high-speed exercise. Objective There is a moderate evidence that EIPH can have a negative impact on horses performance. However, there is very low quality evidence that horses affected by EIPH have impaired fitness parameters such as blood lactate. Aim of the present work is to evaluate some performance indices in a population of Standardbred racehorses with EIPH by means of treadmill exercise testing. Material and Methods Sixteen Italian Standardbred racehorses (average age 3.1±1.0 y.o., 10 males, 6 females), at the same level of performance and at the same stage of their training, were selected. All horses underwent an accurate clinical examination, that allowed to rule out any overt disorder. After two days of familiarization, they underwent a treadmill endoscopy, which ruled out the presence of any dynamic upper airway obstruction, and an endoscopy after the exercise. The latter allowed the categorization of the horses in two groups: 8 horses with no evidence of EIPH, and 8 horses with grade ≥1 of EIPH. Then the horses performed an incremental exercise test on a high speed treadmill. During the test heart rate was monitored with a pulsometer. Blood samples were taken with a 14G teflon venous catheter placed in the jugular vein, and plasma lactate was measured with an enzymatic colorimetric method. Data were analyzed by a specific software and the speed at 4 mmol/L (VLa4), the speed at 200 bpm of heart rate (V200), the maximum heart rate (HRmax), the peak of lactate (Lamax), and the lactate and heart rate at 1, 5 and 30 minutes after exercise were calculated. Data for both groups were statistically compared by T-student test for unpaired sample, and statistical significance was set at p<0,05. Results Concerning VLa4, HRmax, Lamax and lactate after exercise, no differences were observed between the two groups. There was a significant (p<0,05) lower V200 (Fig. 1) and a highly significant lower (p<0,01) heart rate at 30 minutes after exercise (Fig. 2) in EIPH group. Conclusion As already described, very few parameters differ between EIPH and non EIPH horses. The lower V200 in EIPH horses may suggest a negative impact of the disease on performance.