2.2.3 Right-sided congestive heart failure
The term right-sided CHF refers to increased right ventricular filling pressure and consequent increased pressure in the right atrium (RA) and in the systemic veins This may result in the formation of ascitic fluid, pleural fluid, and peripheral oedema. In the horse, subcutaneous oedema in dependant areas such as the ventral abdomen, sheath and distal limbs is the predominant sign. This must be distinguished from other causes of oedema formation (Chapter 3, Table 3.3). In the horse, left-sided CHF usually progresses rapidly to right-sided CHF, because of complex changes in pulmonary vasculature. In many horses, right-sided CHF is the first sign of left-sided heart disease which is noticed by owners. This is in marked contrast to some other species such as dogs in which disease affecting the left side of the heart rarely results in right-sided CHF.