The use of SIFT-MS in profiling the faecal volatile metabolome in horses with colic: a pilot study

SIFT-MS is used for the first time in profiling the volatile organic profile in faecal headspace in two groups of horses admitted to an equine hospital, one group with acute intestinal disease (colic) affecting the large colon, plus a control group of similarly managed horses admitted for non-gastrointestinal/metabolic reasons (e.g. acute orthopaedic injury). Compounds in faecal headspace which show statistically significant concentration differences between the groups are acetone and methanol. In addition, some ions at various m/z values show significantly different ion counts between the groups. Further information may be gleaned by using multivariate statistics in evaluating the differences between the two horse groups. Principal components analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were evaluated for reducing the dimensionality of the SIFT-MS data, and OPLS-DA was found to be best at discriminating between the groups, particularly with SIFT-MS data acquired using the H3O+ precursor ion. Analysis of these data also show the significance of ammonia as a discriminating ion. These results show that SIFT-MS may potentially be used on the headspace of horse faecal samples for detecting altered microbial fermentation associated with acute intestinal disease of the colon