5-HTP (5-hydroxytryptophan) is a supplement extracted from the seeds of a West African shrub (Griffonia simplicifolia).
The human body manufactures 5-HTP from L-Tryptophan, a natural amino acid found in most dietary proteins. However, eating food that contains L-tryptophan does not significantly increase 5-HTP levels.
As a supplement, 5-HTP may work by increasing levels of serotonin (also known as 5-HT), one of the neurotransmitter chemicals that carries messages between brain nerve cells. 5-HTP is a popular human supplement - and is used for both mood and anxiety disorders. A typical human dose of 5-HTP is in the range of 300-500 mg a day.
The use of 5-HTP for dogs is controversial, and potentially very dangerous. A study at the Tufts University School of Medicine found that 1 mg per pound of dog weight twice a day, was beneficial in reducing canine aggression. However, an analysis of accidental 5-HTP ingestion by dogs found that a dose of as little as 10 mg per pound of dog weight could be toxic and produce serotonin syndrome.