Feline lower urinary tract disease (FLUTD) is a term encompassing multiple conditions affecting the bladder and urethra of cats. FLUTD is the leading cause of life-threatening urethral obstruction (UO) in male cats. The exact cause of FLUTD-related UO remains unclear, although it is accepted that stress and environmental factors play a major role. Investigation of FLUTD is important for prevention and to improve treatments for this devastating disease.There is a growing body of evidence that FLUTD has an association with the season. This has lead to the thought that an association may exist between rising sex-hormone levels and development of FLUTD-related UO. Supporting evidence is found in human medicine whereby a recent study examined urine metabolomics in women with interstitial cystitis. They found that the level of a particular testosterone metabolite (etiocholanolone) was able to delineate between affected and non-affected individuals with a high degree of accuracy. Metabolomics is a powerful, non-invasive method to examine thousands of biomarkers. It’s being used to improve understanding of the pathogenesis of disease, and to advance diagnostics and treatments. Although this is a burgeoning area in human medicine, very little is known in cats. Currently, it is the only technique available to look at large numbers of testosterone metabolites in this species.  We will use a targeted metabolomics approach to investigate testosterone metabolites in urine from cats with and without FLUTD-related UO. Not only is this important work in contributing to the understanding of FLUTD-related UO, it will also increase our knowledge of the feline urine metabolome – of which, very little is currently known.