What is the best test for respiratory pathogens?

Infectious respiratory disease is commonly encountered in equine practice. Several studies have shown that the principle respiratory pathogens of importance in the UK are equine influenza virus (EIV), equine herpesviruses-1 and -4 (EHV-1 and EHV-4) and Streptococcus equi. One of the challenges in recognising infectious respiratory disease is that in most outbreaks horses with suggestive clinical signs of fever, nasal discharge, lymphadenopathy and cough form the minority of cases, with the majority developing either mild or asymptomatic disease. This is further complicated by the lack of differentiating clinical signs in many horses. This means that although the ‘textbook’ cases of EIV, EHV and S. equi infection may be clinically distinctive, the large majority of overt clinical cases simple present as nondifferentiated infectious respiratory disease. The relative role of other respiratory pathogens in the UK is less clear partly because systematic surveillance for the full spectrum of respiratory pathogens is not carried out ...