“…The reports in this issue by Schwarzwald et al (2006) and Uhlhorn et al (2006) illustrate a key feature of the functional relationship between the equine cardiovascular and respiratory systems. In other species, notably man (Haselton 1973) and cattle ), respiratory disease, or alterations in respiratory function, have profound effects on the cardiovascular system and frequently result in right-sided cardiac failure. The equine cardiovascular system, however, is generally capable of maintaining normal right-sided function in the face of respiratory disease, even chronic lower respiratory tract diseases that cause severe reduction in respiratory function (Dixon 1978).…”