Hypostatic Pneumonia

Hypostatic pneumonia is caused by passive or dependent congestion of the lungs, a condition most commonly seen in older or debilitated animals. Recumbent animals, such as those recovering from anesthesia, can develop hypostatic pneumonia if not repositioned regularly. Blood is unable to pass readily through the vasculature of the lung, which can lead to a shift in fluid from the circulatory to the pulmonary spaces. It often occurs secondary to some other disease process causing chest pain (eg, congestive heart failure). Shallow respiration can lead to improper ventilation of the dependent lung, loss of surfactant activity, and accumulation of respiratory secretions and inflammatory exudate in lower airways. Compression of the abdominal contents in recumbent patients restricts the downward movement of the diaphragm, reducing tidal volume and ventilation of alveoli. Coughing is not always a prominent clinical sign, but as the condition progresses, dyspnea and cyanosis become apparent. Secondary bacterial infection is common. Radiographs reveal increased pulmonary density, and the mediastinal space may show atelectasis. The animal’s position must be changed hourly. Exercise should be encouraged insofar as it is compatible with the animal’s condition. If a primary cause can be determined, specific therapy should be instituted. Use of narcotics and sedatives should be minimal to encourage movement and to avoid suppression of the cough reflex. Proper hydration is important, but overhydration may increase congestion and should be avoided.