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Interbreed variation in serum serotonin (5-hydroxytryptamine) concentration in healthy dogs

Höglund, K., Häggström, J., Hanås, S., Merveille, A.-C., Gouni, V., Wiberg, M., Lundgren Willesen, J., Entee, K.Mc, Mejer Sørensen, L., Tiret, L., Seppälä, E.H., Lohi, H., Chetboul, V., Fredholm, M., Lequarré, A.-S., Ljungvall, I.
Journal of veterinary cardiology 2018 v.20 no.4 pp. 244-253
Cavalier King Charles Spaniel, blood serum, breed differences, clinical trials, dogs, echocardiography, enzyme-linked immunosorbent assay, females, models, regression analysis, serotonin, storage time
Serotonin (5-hydroxytryptamine [5-HT]) has several biological functions. In different species, excessive 5-HT has been linked to valvular lesions, similar to those seen in dogs with myxomatous mitral valve disease. Previous studies suggest higher 5-HT in healthy Cavalier King Charles Spaniels (CKCSs), a breed highly affected by myxomatous mitral valve disease, compared to other breeds.To investigate potential interbreed variation in serum 5-HT in healthy dogs.483 healthy dogs of nine breeds aged 1–7 years.Dogs were examined at five European centers. Absence of cardiovascular, organ-related, or systemic diseases was ensured by thorough clinical investigations including echocardiography. Serum was frozen and later analyzed by enzyme-linked immunosorbent assay (ELISA).Median 5-HT concentration was 252.5 (interquartile range = 145.5–390.6) ng/mL. Overall breed difference was found (p<0.0001), and 42% of pairwise breed comparisons were significant. Univariate regression analysis showed association between serum 5-HT concentration and breed, center of examination, storage time, and sex, with higher 5-HT in females. In multiple regression analysis, the final model had an adjusted R2 of 0.27 with breed (p<0.0001), center (p<0.0001), and storage time (p=0.014) remaining significant. Within centers, overall breed differences were found at 3/5 centers (p≤0.028), and pairwise comparisons within those centers showed breed differences in 42% of comparisons. Among the included breeds, Newfoundlands, Belgian Shepherds and CKCSs had highest 5-HT concentrations.Interbreed variation in serum 5-HT concentration was found in healthy dogs aged 1–7 years. These differences should be taken into account when designing clinical studies.