L-Theanine for Dog Anxiety: Does It Work? Evidence

L-theanine is an amino acid found in tea and one of the most common active ingredients in dog calming chews, often combined with melatonin, chamomile, magnolia or colostrum. Its controlled evidence in dogs is a single laboratory trial with five treated dogs and five on placebo, plus an open-label study in storm-sensitive dogs. Combination products built around L-theanine have little more: one controlled shelter study found a very small effect, and colostrum-based blends have only manufacturer field trials.

Key takeaways

• In a laboratory study, 5 fearful Beagles on L-theanine approached an unfamiliar person more than 5 on placebo.
• An 18-dog storm-sensitivity study reported improvement over successive storms, but was open-label with no placebo.
• A controlled study of Solliquin (L-theanine + magnolia + phellodendron + whey protein) in shelter dogs found only a small increase in light rest and no change in fecal cortisol.
• Colostrum-plus-L-theanine blends have manufacturer field trials without placebo groups.
• Evidence for one situation (fear of strangers, storms) does not transfer to separation anxiety or travel stress.

What is L-theanine?

L-theanine is an amino acid in tea leaves that crosses into the brain and is thought to influence GABA, serotonin and dopamine signaling and to promote relaxed alertness rather than sedation. Those mechanisms explain why it is being studied. They are not clinical outcomes, and human trials of L-theanine for stress cannot simply be applied to dogs.

What the canine evidence shows

The laboratory fear trial

Researchers identified Beagles that were fearful of unfamiliar people and gave L-theanine chewable tablets (Anxitane) to five and placebo to five. Treated dogs showed more approach and interaction with an unfamiliar person than placebo dogs. It is controlled evidence, but with five dogs per group and a laboratory fear model, one or two unusual dogs could change the result.

The storm-sensitivity study

In a prospective study, owners of storm-sensitive dogs gave L-theanine during storm season; 18 dogs completed it. Global anxiety scores and time to return to normal improved over successive storms, and owners reported fewer fear behaviors. But the study was open-label: owners knew their dogs were treated, there was no placebo group, and storms vary in intensity. Expectation and chance cannot be separated from a treatment effect.

Combination products

L-theanine with magnolia and phellodendron (Solliquin)

Solliquin combines L-theanine with extracts of magnolia and phellodendron bark and whey protein. In a 2021 controlled study of dogs entering a shelter, stress was measured with fecal cortisol and activity monitors. The Solliquin group had an increase only in “light rest” (P = 0.050) compared with control dogs, and no difference in deep rest, other activity measures or fecal cortisol. A product that changes one of several outcomes at the edge of significance has not been shown to reduce stress.

L-theanine with colostrum (Composure and similar)

Several popular chews pair L-theanine with a “colostrum calming complex” (bovine colostrum peptides) and thiamine. The evidence we could find is a manufacturer field trial in 30 dogs and 10 cats with situational anxiety, without a placebo group, and white papers on the colostrum complex. That is not controlled evidence. The colostrum ingredient’s claimed action resembles alpha-casozepine, a milk-derived peptide with placebo-controlled trials, but evidence for alpha-casozepine does not transfer to a different peptide blend: see alpha-casozepine for dogs.

Why the evidence stays narrow

The available studies involve fear of unfamiliar people and storm sensitivity. They do not establish benefit for separation-related problems, generalized anxiety, travel stress or veterinary-visit fear. Behavior problems with different triggers should not be treated as one condition.

Safety

L-theanine has been well tolerated in dog studies. As with any calming product, check with your veterinarian if your dog takes other behavior medicines, and be cautious with human products that may contain xylitol or caffeine-containing tea extracts.

How to read the label

• Is L-theanine the main active, and is the amount in mg stated? The studies gave a commercial L-theanine tablet twice daily, sized by body weight.
• What else is in it? Melatonin, chamomile, hemp seed and tryptophan each have their own, often weaker, evidence — see melatonin and tryptophan.
• Does the evidence cited match your dog’s problem?

For a full checklist, see How to check a dog calming supplement label.

Dog Supplement Facts evidence status

INSUFFICIENT

One very small controlled trial and one open-label study for L-theanine alone; one controlled study with a marginal effect for an L-theanine–magnolia combination; and uncontrolled field trials for colostrum blends. Under our rating rules, L-theanine and its combination products are rated insufficient.

When a supplement is not enough

If your dog panics, injures itself, destroys property or cannot settle, talk to your veterinarian. Behavior modification and prescription medicines have much stronger evidence than any calming chew.

Related Dog Supplement Facts content

• Alpha-Casozepine for Dogs
• Melatonin for Dogs With Anxiety
• Do Calming Chews for Dogs Work?
• Dog Calming & Stress Guide

References

1. Araujo JA, et al. ANXITANE tablets reduce fear of human beings in a laboratory model of anxiety-related behavior. J Vet Behav. 2010;5(5):268–275. doi:10.1016/j.jveb.2010.02.003
2. Pike AL, Horwitz DF, Lobprise H. An open-label prospective study of the use of L-theanine (Anxitane) in storm-sensitive client-owned dogs. J Vet Behav. 2015;10(4):324–331. doi:10.1016/j.jveb.2015.04.001
3. Stillo T, et al. The effects of Solliquin administration on the activity and fecal cortisol production of shelter dogs. J Vet Behav. 2021;45:10–15. doi:10.1016/j.jveb.2021.05.001
4. VetriScience Laboratories. Field trial of Composure products with the new Colostrum Calming Complex (C3). Manufacturer white paper. https://info.vetriscience.com/white_papers/VSD53%20Compos%20Clinical.pdf