In horses, VetARDS is a rare, but distinct, clinical condition in foals younger than nine months of age. | Photo: Anne M. Eberhardt/The Horse

Acute respiratory distress syndrome (ARDS) causes rapidly progressive and severe respiratory failure and is associated with high mortality in affected patients. First described in critically ill humans more than 50 years ago, ARDS is now recognized as a rare cause of respiratory failure in several veterinary species including horses, where it is referred to as veterinary ARDS (VetARDS).

ARDS and VetARDS develop as a complication when a primary disease or injury triggers overwhelming and uncontrolled inflammation in the lung. This inflammatory response causes the hallmark features of ARDS: severe pulmonary damage and edema, respiratory dysfunction, and profound hypoxemia (low oxygen in the blood). Pneumonia and conditions associated with severe systemic inflammation, such as sepsis, represent the most common risk factors for ARDS and VetARDS. Other potential risk factors include smoke inhalation, severe trauma, aspiration of stomach contents, and near drowning.

In horses, VetARDS is a rare, but distinct, clinical condition in foals younger than nine months of age. Previously, this condition was referred to as acute interstitial or bronchointerstitial pneumonia. Bacterial pneumonia is the most common predisposing cause of VetARDS in these foals. There does not appear to be a single bacterial pathogen associated with VetARDS in foals but Rhodococcus equi, Klebsiella sp. and Streptococcus sp. have all been identified with VetARDS. Sepsis represents the most likely risk factor in neonatal foals and conditions consistent with VetARDS have been reported in adult horses after smoke inhalation or near drowning