Partial atrioventricular septal defect in an adult sport horse.

A partial atrioventricular septal defect, represented as a large ostium primum atrial septal defect and common (bridging) atrioventricular valve leaflets with cleft septal leaflet of the mitral valve, was diagnosed incidentally in a nine-year-old warmblood gelding used for show jumping. Initial examination findings and a three-year follow-up are documented in this report. The horse was first presented for the evaluation of chronic coughing. A left-sided, grade 4/6 holosystolic (band-shaped) murmur was identified along with a similar right-sided, grade 3/6 heart murmur. Echocardiography revealed a 6.4 cm diameter communication in the ventral atrial septum, considered an ostium primum atrial septal defect, with bidirectional shunting. A hypertrophic septomarginal trabecula, a thickened tricuspid valve, a cleft septal leaflet of the mitral valve, moderate mitral and tricuspid regurgitation likely related to leaflet prolapse, mild aortic regurgitation, and signs of moderate right ventricular volume overload were found as well. Electrocardiography showed no arrhythmias neither at rest nor during treadmill exercise. The owner continued to use the horse for show jumping. No exercise intolerance or other signs of disease were noted. Follow-up examination was performed three years after initial presentation. Contrast echocardiography confirmed the presence of right-to-left shunting through the atrial septal defect. Compared with the initial examination, the left ventricular internal diameter on M-mode echocardiography had increased. Occasional ventricular premature depolarizations were noted on the resting and exercise electrocardiogram. This is the first description of a clinically asymptomatic partial atrioventricular septal defect in an adult sport horse.

Equine atypical myopathy: A metabolic study.

Atypical myopathy (AM) is a potentially fatal disease of grazing horses. It is reportedly caused by the ingestion of sycamore seeds containing toxic hypoglycin A. In order to study metabolic changes, serum and urine samples from nine horses with atypical myopathy and 12 control samples from clinically healthy horses were collected and then analysed using a high-performance liquid chromatography coupled with tandem mass spectrometry; serum metabolic profiles as the disease progressed were also studied. Metabolic data were evaluated using unsupervised and supervised multivariate analyses. Significant differences were demonstrated in the concentrations of various glycine conjugates and acylcarnitines (C2-C26). Moreover, the concentrations of purine and pyrimidine metabolites, vitamins and their degradation products (riboflavin, trigonelline, pyridoxate, pantothenate), and selected organic and amino acids (aspartate, leucine, 2-oxoglutarate, etc.) were altered in horses with AM. These results represent a global view of altered metabolism in horses with atypical myopathy.