A device for the collection of discrete blood samples from large animals has been developed to allow studies of physiology to be undertaken without the confounding effect of restraint. A microprocessor controlled unit (measuring 180 × 110 × 90 mm), weighing less than 1-2 kg, is mounted on the back of the experimental subject using a simple harness. A sampling line is connected to a previously inserted jugular vein catheter. Samples of blood (approx. 5 ml) are collected at pre-determined times following a start time which can be delayed by up to 48 h to allow the subject to recover from any effects of attachment of the sampler. The results from three studies suggest that the device offers a novel way to overcome a number of difficulties which occur when conventional methods are used to collect blood in experiments.
