Central blood volume and lung extravascular thermal volume in dogs with dirofilariasis

Central blood volume, lung extravascular thermal volume, cardiac output, and pulmonary and systemic vascular pressures were measured in clinically normal and heartworm-infected dogs. Central blood volume and cardiac output were significantly (P less than 0.05) decreased in heartworm-infected dogs compared with the in normal dogs. Pulmonary vascular resistance, total peripheral resistance, mean pulmonary artery, pulmonary artery wedge, and pulse pressures were significantly increased in heartworm-infected dogs compared with that in normal dogs. Significant differences between normal and heartworm-infected dogs were not found in lung extravascular thermal volume, pulmonary extravascular tissue weight, or extravascular lung water to extravascular dry-weight ratio. Lung extravascular thermal volume overestimated gravimetric pulmonary extravascular tissue weight by approximately 16%. A significant correlation (R = 0.83) existed between pulmonary extravascular tissue weight and lung extravascular thermal volume for all dogs.