Relationship between clinical signs and results of impulse oscillometry in pigs originating from the field

• IOS is suitable to detect pulmonary alterations in pigs originating from the field.
• Clinical data correlated with IOS parameters mainly representing the lung periphery.
• The new parameter AX is sensitive to changes in peripheral lung function.
• Clinical data led to a mean r2 of 0.52 for IOS variations.
• Further studies should reveal the proportion of variance undefined by clinical data.

The aim of the present study was to assess the contribution of clinical data to the variability of impulse oscillometric test results observed previously by Püllen et al. (2014). Fifty-eight German hybrid pigs from 29 different herds with unknown respiratory status were examined in the context of routine diagnostics as part of herd health service. Routine clinical examination was extended to a total set of 29 parameters, representing detailed clinical signs of the respiratory system, and to lung function testing applying the impulse oscillometry system (IOS). The resulting linear relationship between clinical data and variables of pulmonary mechanics had a mean r2 of 0.52. Clinical parameters predominantly representing the lower respiratory tract closely correlated with established impulse oscillometric indices reflecting peripheral airways. Because of a restricted relationship between pulmonary functional disorders and clinical data, additional diagnostic methods are required to reveal the proportion of variance undefined by clinical examination.