Tryptophan, serotonin and dog behavior
Serotonin, also known as 5-hydroxytryptamine (5-HT), has been firstly isolated and described by Maurice Rapport and colleagues (Rapport et al., 1948), after decades of research on a vasoconstrictor substance suspected of being contained in platelets (Reid & Brick, 1942; Zucker, 1944). After its discovery, several studies have been done to identify its location and function and 5-HT was quickly identified in many tissues, including the brain, lungs, kidneys, platelets and gastrointestinal tract. In addition to its role in platelet function, Brodie & Shore (1957), firstly proposed a role of 5-HT as a neurotransmitter, based on the localization of 5-HT receptors in specific areas of the vertebrate brain (Twarog & Page, 1952; Amin et al., 1954).
The link between TRP metabolism, serotonin and behavior has been the subject of considerable interest and discussion in the dog. The use of TRP in the behavioral clinic of the dog is still controversial. While there is evidence of efficacy of products containing TRP and other sub-stances during anxiety syndrome and stress, the use of only TRP in the control of canine aggression has given, until now, inconclusive results.