Reducing the invasiveness of obtaining blood-borne measures in animals

To overcome the limitations associated with routine blood collection methods in welfare research, we are developing a new technique that combines low frequency ultrasound with a small electric current (electrosonophoresis). Portable instrumentation, positioned at the skin surface, delivers a brief burst of ultrasound and low electric field, creating a brief transdermal flux from underlying blood vessels into extracellular fluid and to the skin. The technique allows many analytes present in blood to be collected and measured at the skin surface. In humans, the method is without sensation and is innocuous. Actual blood removal is not required, and repeated measure over a short time period does not cause discomfort. In animals accustomed to human handling, no behavioural disturbance has been seen when using the instrumentation. Large cellular substances, such as red blood cells, cannot be collected by this method, but analytes, including hormones, sugars, free fatty acids, immunoglobulins and lactate, have been collected and measured with a high correlation (r2≥ 0.89) to blood levels over a wide physiological range of change. The low invasiveness of use, the removal of the need to extract actual blood fluid, and the low stressfulness of the technique, suggest that this may be a powerful tool for welfare studies.