Serum Trimethylamine N-Oxide as a Diagnostic and Prognostic Biomarker in Dogs with Chronic Kidney Disease: A Pilot Study.

Trimethylamine N-oxide (TMAO) is known to increase in human cardiovascular, metabolic, and renal diseases. In human medicine, TMAO has recently been utilized as a diagnostic and prognostic biomarker for renal dysfunction, and research is ongoing regarding its potential as a therapeutic target. This study aimed to evaluate the diagnostic and prognostic potential of TMAO as a supportive biomarker in dogs with chronic kidney disease (CKD). To assess its diagnostic utility, TMAO concentrations were compared between a CKD group ( = 32) and a healthy control group ( = 32). In addition, patients with CKD were subdivided into stages 2 ( = 12), 3 ( = 11), and 4 ( = 9) and compared individually with the healthy controls. For prognostic evaluation, the CKD group was monitored over six months, and the TMAO levels were compared between survivors ( = 18) and non-survivors ( = 14). The TMAO concentrations showed a highly significant difference between patients with CKD and healthy controls ( < 0.0001). Patients with each different CKD stage exhibited statistically significant differences compared with the healthy controls ( < 0.05). Furthermore, the median TMAO levels tended to increase with advancing CKD stage; however, the differences among stages were not statistically significant. In addition, within the CKD group, TMAO concentrations were significantly higher in non-survivors than in survivors at the six-month follow-up ( = 0.0142). This pilot study highlights the potential of TMAO as a supportive renal biomarker for diagnostic and prognostic evaluation in canine CKD.