A biomarker is a naturally occurring molecule, enzyme or gene found in blood, other bodily fluids or tissue that can be measured objectively as an indicator of a pathogenic process or normality. While some biomarkers are only research tools, there is now a plethora of markers suggested for the investigation of enteropathies in dogs and cats. None are the holy grail of a test that will give a diagnosis with 100 % specificity and sensitivity. However some may be more useful and reliable than others. This lecture will discuss what tests are available to practitioners and whether they are worthwhile as one should only do a test if the result is going to alter the patient’s outcome.