It is proposed to develop the oscillometric method of measuring blood pressure and to apply it to animals to indicate true mean arterial pressure. Specifically, studies will be carried out to develop suitable member-encircling occluding cuffs for compressing an underlying artery and to determine the correct dimensions for such cuffs so that the counterpressure for maximum oscillations in the occluding cuff is true mean arterial pressure. The oscillations in the underlying artery will be detected by measurement of the oscillations in cuff pressure. The oscillometric method for detecting true mean arterial pressure indirectly will be investigated in animals with hypo and hypertension. Finally, an automated instrument will be developed to indicate true mean arterial pressure. The instrument will be evaluated in animals undergoing treatment in the School of Veterinary Medicine.