Resuscitation of an anaesthetised foal with uroperitoneum and ventricular asystole

A 2‐day‐old male Quarter Horse foal was diagnosed with uroperitoneum and ruptured bladder. Intravenous fluid therapy was initiated prior to anaesthesia and repeated unsuccessful attempts were made to drain the abdomen of accumulated urine. Prior to anaesthesia the foal exhibited clinical signs of abdominal compartment syndrome. When anaesthetised the accumulated urine was drained by free flow through a small abdominal stab incision after aseptic site preparation. A few minutes later electrocardiography indicated second degree atrioventricular block which progressed into third degree atrioventricular block and ventricular asystole. The foal was resuscitated by closed chest compressions, mechanical ventilation, sympathomimetic and antimuscarinergic drugs. When anaesthetising these neonatal patients one must be prepared to handle potentially fatal cardiac arrhythmias and, prior to surgery, the danger posed by increased intra‐abdominal pressure should be weighed against the need for diluting plasma potassium.     

Evaluation of heart rate and rhythm during exercise

Heart rate and rhythm can readily be monitored during exercise. Although there is considerable variation depending on the athletic discipline, exercise can be considered to be one of the most physiologically demanding times for the cardiovascular system. Assessment of heart rate during exercise typically provides information regarding fitness and the intensity of exercise, and on some occasions may provide an early indication of disease. Cardiac causes of poor performance occur relatively infrequently in comparison with disorders of the musculoskeletal and respiratory systems. Nevertheless, exercise induces cardiac hypertrophy, which predisposes athletes to valvular regurgitation and arrhythmias. Consequently cardiac murmurs and arrhythmias are frequently present in equine athletes, whereupon the clinical significance can be difficult to determine. Undertaking an exercise test to identify exercise‐induced arrhythmias is important in the assessment of poor athletic performance and the risk of sudden cardiac death during exercise. This paper describes the assessment of heart rate and rhythm during exercise. Most research has been undertaken on racehorses but, where data are available for other disciplines, they have been included. Considerations regarding the choice, type and design of exercise test were detailed in the first paper in this series.