The aim of this study was to test, if a better differentiation can be made between horses suffering from RAO (recurrent airway obstruction), IAD (inflammatory airway disease) and healthy ones by using the flow - metric system in combination with CO2 induced hyperventilation. The following parameters were analyzed: Clinical Score, respiratory rate (RR), tidal volumen (TV), peak expiratory summed flow (PEsf) and peak inspiratory summed flow (PIsf).
Thirthy six horses were included in the study. From each horse the data was collected during normal breathing at rest and during CO2 induced hyperventilation. Additionally a BAL (Bronchoalveolar Lavage) cytology was taken, a clinical examination and an endoscopic examination were performed and finally the arterial blood gases were analyzed.
According to the percentage of PMN (polymorph nuclear) cells in the BALF cytology, the horses were assigned to one of the following groups:
healthy horses, horses with IAD and RAO affected horses.
It was significant, that the RAO group contained older horses with higher clinical scoring than the non-RAO group.
Apart from PEsf, no significant group difference was found.
RAO affected horses showed the highest variance in respiratory frequency at rest. During induced hyperventilation in all groups the mean respiratory rate increased as it was expected. However, the RAO group showed only a small increase in respiratory frequency. Despite these trends, respiratory rates between the three groups as well in rest as during hyperventilation were not significantly different. PEsf was significantly higher in the RAO group than in the non-RAO (p=0.046).
This study showed that the flow - metric method in combination with CO2 induced hyperventilation is a suitable noninvasive technique for detecting horses affected with obstructive lung disease.