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The amount of seretonin in blood differs between dog breeds

Last changed: 24 January 2019
Close up of dog head resting on table top. Photo

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.

Link to the publication


Höglund K, Häggström J, Hanås S, Merveille A-C, Gouni V, Wiberg M, Lundgren Willesen J, Mc Entee K, Mejer Sørensen L, Tiret L, Seppälä E.H, Lohi H, Chetboul V, Fredholm M, Lequarré A-S, Ljungvall I. Inter-breed variation in serum serotonin (5-HT) concentration in healthy dogs. Journal of Veterinary Cardiology, (2018), volume 20, issue 4, pages 244-253.


Katja Höglund
Senior Lecturer at the Department of Anatomy, Physiology and Biochemistry (AFB); Division of Anatomy and Physiology

Telephone: 018-672118