An Increase in the Urinary Levels of Prostaglandin D and Platelet-activating Factor Metabolites in Dogs with Mast Cell Tumor

The diagnosis of canine mast cell tumor (MCT) via cytology carries the risk of triggering life-threatening anaphylactic reactions due to massive histamine release. Since mast cells release various lipid mediators, which are excreted in urine, we aimed to explore urinary lipid metabolites as potential non-invasive diagnostic markers for MCT. Liquid chromatography-mass spectrometry-based analysis detected 32 types of lipid metabolites in the urine of MCT dogs. Among these, urinary levels of 15-deoxy-δ-12,14-PGJ, lyso-PAF, 9,10-DiHOME, and 12,13-DiHOME were significantly elevated in MCT dogs compared to healthy dogs. These urinary lipid metabolites could serve as novel non-invasive biomarkers for canine MCT.