Arterial blood gas analysis in 53 racehorses with a diagnosis of Small Airway Inflammatory Disease (SAID)

In 53 racehorses with a mean age of 4.5 years old presented for poor performance, Small Airway Inflammatory Disease (SAID) was diagnosed by bronchoalveolar lavage (BAL). Thirty of these horses (58.5%) had arterial pCO2 above normal range (> 46 mmHg), while pO2 was within normal range (> 80 mmHg) in both hypercapnic (group A) and normocapnic (group B) horses although pO2 was significantly lower in group A horses. The horses were subsequently subdivided into two groups according to the duration of symptoms (group 1: less than 4 weeks; group 2: longer than 4 weeks). Horses from group 2 had significantly higher values of pCO2 (p < 0.01) , HCO3- (p < 0.01) and TCO2 (p < 0.05) when compared to horses from group 1. It was concluded that the duration of the inflammatory process may play a role in the alteration of blood/alveolar gas exchanges and acid-base status in SAID affected racehorses.