L-Tryptophan
Trp · essential amino acid
Mechanism
L-tryptophan is the metabolic precursor of the neurotransmitter serotonin (5-HT), which is attributed a mood- and arousal-modulating role. The rationale behind calming products is that increased tryptophan intake raises central serotonin synthesis. Evidence in the horse is inconsistent, however: Bagshaw et al. (1994) and Noble et al. (2008) found no consistent calming effect with oral dosing, and some studies even described mild excitation at low doses. A reliable sedative effect in the horse is therefore not established. Important for competition: L-tryptophan is currently not on the FEI Equine Prohibited Substances List, but the status of related calming-active substances changes continually.
Cautions
- · Effect in horses not reliably established; contradictory study data
- · High oral doses: literature reports possible adverse effects (incl. ataxic/excitatory reactions)
- · FEI: currently not listed, but check the status of calming-active substances before competition
Sources
Knowledge connections
Frequently asked questions
Is L-Tryptophan a feed or a veterinary medicine for horses?
Equiterna classes L-Tryptophan as “Complementary feed”. Legal framework: Regulation (EU) 2019/6 / TAMG (DE/AT), Feed Regulation (EC) 767/2009.
Is L-Tryptophan allowed at FEI competitions?
In the profile, L-Tryptophan is listed with the FEI status “Not listed”. The current FEI list is authoritative, so please check its latest version.
Which dosage do the sources give for L-Tryptophan?
Stated in the profile: Study reference range 0.1–0.2 g/kg BW/day orally; approx. 5–10 g/animal/day for a large horse (~500–600 kg) as a supplement. Discuss use with a vet. This is information from the literature, not an instruction for an individual horse.
Which sources are there for L-Tryptophan?
The profile cites: PMID:18537776, Bagshaw 1994 Appl Anim Behav Sci, and FEI EPSL 2024.
Usage note
This content is for information and education. It does not replace veterinary diagnosis or treatment. If your horse shows signs of illness, consult a veterinarian.
“Nothing forced can ever be beautiful.”
Equiterna is an intermediary platform for equine knowledge, marketplace and tools — not a veterinary-medicines dealer, veterinary practice or pharmacy. Compound information is source-attributed (PubMed, specialist journals, NRC/GfE, EU regulations) and free of healing claims. Legal framework: Regulation (EU) 2019/6 / TAMG (DE/AT), Feed Regulation (EC) 767/2009, FEI Prohibited Substances List, HWG.