A pilot study investigating circulating trimethylamine N‐oxide and its precursors in dogs with degenerative mitral valve disease with or without congestive heart failure

BACKGROUND: Pathophysiologic mechanisms for the development and progression of degenerative mitral valve disease (DMVD) remain elusive. Increased concentrations of circulating trimethylamine N‐oxide (TMAO) and its precursors choline and l‐carnitine are associated with the presence and severity of heart disease in people. OBJECTIVES: To determine if differences exist in plasma concentrations of TMAO, choline, or l‐carnitine among dogs with DMVD and congestive heart failure (CHF), dogs with asymptomatic DMVD, and healthy control dogs. ANIMALS: Thirty client‐owned dogs: 10 dogs with CHF secondary to DMVD, 10 dogs with asymptomatic DMVD, and 10 healthy control dogs. METHODS: A pilot cross‐sectional study in which echocardiography was performed and fasting plasma concentrations of TMAO, choline, and l‐carnitine (total and fractions) were measured. RESULTS: TMAO (P = .03), total l‐carnitine (P = .03), carnitine esters (P = .05), and carnitine esters to free carnitine ratio (E/F ratio; P = .05) were significantly higher in dogs with CHF compared to those with asymptomatic DMVD. TMAO (P = .02), choline (P = .01), total l‐carnitine (P = .01), carnitine esters (P = .02), free carnitine (P = .02), and E/F ratio (P = .009) were significantly higher in dogs with CHF compared to healthy controls. CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs with CHF secondary to DMVD had higher concentrations of TMAO compared to both asymptomatic DMVD dogs and healthy controls. Larger prospective studies are warranted to determine if TMAO plays a role in the development or progression of DMVD or CHF.