Abstract

MORALES, Abelardo et al. AVFT [online]. 2015, vol.34, n.3, pp.35-39. ISSN 0798-0264.

The aim of this study was to describe hypertrophic cardiomyopathy occurring in conjunction with exercise induced pulmonary hemorrhage in Thoroughbred horses in the national racetrack “La Rinconada”, Caracas Venezuela. The study included 26 equine Thoroughbreds, of which 20 were male and six were female, within 2-4 years old. All horses had previous episodes of pulmonary hemorrhage induced by exercise and had no clinical signs consistent with cardiomyopathy, and had a routine diagnostic necropsy. Samples of tissue heart and lungs and other organs were collected, fixed, prepared and stained with Hematoxylin & Eosin (H&E) and special stain Prussian Blue, for light microscopy. On necropsy, all cases revealed hypertrophic cardiomyopathy, specifically left ventricular concentric hypertrophy, with severe obliteration of the left ventricular lumen. There were no valve diseases or mural or valve endocarditis. The average diameter of left ventricular wall was approximately ±9.20 cm (DS: ±0.925). The thickness of the wall of the left ventricle was on average ±6.19 cm (DS: ±0.409). Weight heart was to ±5.11 (DS: ±0.530). Histological lesions showed congestion, edema, and acute pulmonary intra-alveolar and interstitial hemorrhage due to rupture of focal bronchial arterioles, replete with red blood effusion. The Prussian blue special stain was positive for hemosiderophages in all cases studied. Microscopically there is fiber disarray, hypertrophic cardiomyocytes and some fibrosis. The cardiac fibers increase in width, nuclei increase in size. In conclusion these results suggest a close relationship between the developments of exercise-induced pulmonary hemorrhage associated with ventricular concentric hypertrophic cardiomyopathy in Thoroughbred horses.

Keywords : Cardiomyopathy; EIPH; HCV; Pathology; Thoroughbreds.