Polymorphisms in the serotonin transporter gene and circulating concentrations of neurotransmitters in Cavalier King Charles Spaniels with myxomatous mitral valve disease

Abstract Background The neurotransmitter serotonin (5‐HT) affects valvular degeneration and dogs with myxomatous mitral valve disease (MMVD) exhibit alterations in 5‐HT signaling. In Maltese dogs, 3 single nucleotide polymorphisms (SNPs) in the 5‐HT transporter (SERT) gene are suggested to associate with MMVD. Hypothesis/Objectives Determine the association of SERT polymorphisms on MMVD severity and serum 5‐HT concentration in Cavalier King Charles Spaniels (CKCS). Additionally, investigate the association between selected clinical and hematologic variables and serum 5‐HT and assess the correlation between HPLC and ELISA measurements of serum 5‐HT. Animals Seventy‐one CKCS (42 females and 29 males; 7.8 [4.7;9.9] years (median [Q1;Q3])) in different MMVD stages. Methods This prospective study used TaqMan genotyping assays to assess SERT gene polymorphisms. Neurotransmitter concentrations were assessed by HPLC and ELISA. Results TaqMan analyses identified none of the selected SERT polymorphisms in any of the CKCS examined. Serum 5‐HT was associated with platelet count (P