Animals
Nine cardiovascularly-healthy horses classified as American Society of Anesthesiologists (ASA) physical status I or II were used. This number was chosen based on the recommendation of 8 subjects by the American College of Veterinary Internal Medicine (ACVIM) for the number of subjects required to validate noninvasive blood pressure against an invasive technique.14 Health status was based on physical examination with attention to cardiopulmonary auscultation, jugular fill, packed cell volume, total protein, and abbreviated serum chemistry. Horses were aged 2 to 30 years (median: 25) and weighed 308 - 563 kg bwt (median: 473). Quarter horses were overrepresented as a breed. This experiment was performed simultaneously with a study requiring invasive blood pressure monitoring with approval from the ******** Institutional Animal Care and Use Committee.