This study investigated the potential associations of dog characteristics with serum serotonin (5HT) concentration in dogs with degenerative mitral valve disease (DMVD). Client-owned dogs were prospectively recruited at the Veterinary Medical Teaching Hospital of Chungnam National University between 2010 and 2011. Forty-two dogs (22 females and 20 males) were enrolled in this study. DMVD dogs included Maltese (n=12), followed by Shih-tzu (n=10), mixed breed (n=5), Chihuahua (n=4), Miniature schnauzer (n=3), Miniature poodle (n=3), Miniature pinscher (n=1), Pomeranian (n=1), Yorkshire terrier (n=2), and Spitz (n=1). As inclusion criteria for the study, dogs had to show either direct or echocardiographic evidence of DMVD. Platelet count significantly differed among the three groups, as the moderate (P<0.05) and severe groups (P<0.05) showed significantly higher platelet counts than the mild DMVD group. Additionally, significantly higher LVIDd, LVIDs, fractional shortening (FS), and LA:Ao ratios were observed in dogs with moderate (P<0.05) and severe (P<0.05) DMVD compared to the mild group, respectively. Significant positive correlations between serum 5-hydroxytryptamine (5HT) concentration and platelet count (r=0.273, P=0.03), LA:Ao ratio (r=0.459, P=0.001), and LVIDd (r=0.319, P=0.013) were observed in DMVD dogs. Therefore, serum 5HT concentration may be a potential cause of DMVD progression.

• Kun-Ho Song(Laboratory of Veterinary Internal Medicine, College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Korea)
• Sun-Hee Lee(Laboratory of Veterinary Internal Medicine, College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Korea)
• soo jung Lim(Laboratory of Veterinary Internal Medicine, College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Korea)