Canine behavioural problems are very common, one study suggested they occur in up to 90% of dogs. Anxiety, phobia and emotional disorders are also fairly common in our pet dogs. In one study the prevalence estimate for noise sensitivity was 39.2%, 26.2% for general fearfulness, and 17.2% for separation anxiety. So more and more people are seeking help for their dogs. The boom in puppies over the pandemic also saw a rise in certain behavioural challenges in our dogs.

There are many supplements marketed for calming aids – some are better quality than others. The supplement market is not regulated to the same standard as veterinary medicines. This means it’s often down to the individual company to uphold many of their product guarantees and ensure quality and quality of ingredients. So what’s in them, and does it work?

What is on offer?

There are a HUGE number of supplements available for calming in dogs – ingredients range but may include L-Tryptophan, GABA and L-Arginine, L Theanine, Fish protein hydrolysate, melatonin, thiamine and a number of herbal ingredients like Lemon Balm, Passiflora Incarnata and Valarian.

It can be incredibly confusing to know what is best for your dog – and the most important question, do they work?

Do they work?

As usual when it comes to supplements, which are not controlled in the same ways as medicines and do not need to prove that they work to be sold, the evidence is sometimes contradictory and confusing. 

Raw ingredients

The following list is just a small investigation into a few of the ingredients that are seen in calming supplements aimed at dogs.


Tryptophan is an essential amino acid – there are two types of tryptophan: L-tryptophan and D-tryptophan. The only difference between the two types is the orientation of the molecule.

The rationale for the therapeutic use of L-Tryptophan is based on the fact that alterations in the brain L-Tryptophan levels can influence the synthesis of serotonin. Serotonin has important physiological functions in the body, especially in controlling anxiety. It has been suggested that deficiency in tryptophan is more likely to show aggression, depression and moodiness.

One study found that none of the Tryptophan supplemented diets elicited a consistent or significant enough observable response to conclude that the concentrations used (in this particular study) resulted in an improvement in behaviour associated with approaching individuals. 

This was investigated in another study that concluded that intake of diets supplemented solely with Tryptophan or in combination with beet pulp, salmon oil, soy lecithin, and green tea extract does not change anxiety-related behaviour in privately owned dogs. This suggests that the influence of dietary Tryptophan on behaviour of anxious or chronically stressed dogs remains to be established.

In another study animals were randomly assigned to dietary supplementation of L-Tryptophan starting at the 7th week. Each animal was observed during 3.5 months (two weeks for habituation, four weeks without supplementation and eight weeks with supplementation). In dogs, all the stereotypical (abnormal) behaviours, barking and staring decreased. This is a potentially positive outcome and could suggest more research is needed into how effective it could be to help calming.

Does it work? That’s a “maybe”.


Gamma-aminobutyric acid is an important neurotransmitter in the brain and is responsible for relaxing the nervous system.

In one study into aged dogs with behavioural abnormalities, improvement in some behavioural signs was notable without any observable adverse effects. Dogs administered with GABA tended to exhibit improvement in emotional states. It was noted that effects on cognitive dysfunction syndrome were not always observed. GABA administration may improve certain behavioural abnormalities and thus the quality of life of aged dogs.

In human studies they also have some positive outcomes stating ‘the article concludes with further support for the role of the GABA system in anxiety by summarising the current evidence supporting the use of novel GABAergic agents in the treatment of anxiety disorders.’ and showing that anxiety levels may reduce in children with administration of GABA .

Does it work? Probably, but not for everything.

L- Arginine

L – Arginine is an amino-acid – the evidence is sparse for the use of it in dogs but in humans it has been suggested to help with blood flow, including in the brain. This is because in humans it can be seen to help with preventing heart disease and treating arterial disease because it widens vessels. The evidence in dogs is weak for its possible benefits on anxiety disorders.

Does it work? Possibly not, and at best, it’s unproven.

L Theanine

There are very few studies into this in dogs, these are summarised here. The reasoning behind the potential value of l-theanine for treatment of anxiety in dogs is plausible, which means there is potential that it could have some effects on your dog’s anxiety.

However, even though the research in humans is weak, evidence does show potential for a possible benefit. Unfortunately, the current evidence does not allow us to draw firm conclusions.

Furthermore, the research in dogs is also extremely limited and weak! 

Does it work? Although theoretically it could work, it is not possible to say with any confidence whether or not L-theanine will benefit dogs with anxiety. 

Herbal remedies

Many herbal remedies are purported to have calming effects. This is quite plausible, given the sheer numbers of different active chemicals in some plants – and we’re only dealing with the legal ones here! 

Lemon balm

Again, evidence in this field is lacking in dogs. In one review it was suggesting that long term administration relieves stress related effects. Another stated that lemon balm treatments were generally associated with improvements in mood and/or cognitive performance.

Does it work? Probably in humans, insufficient evidence in dogs. 

Passiflora incarnata

As there appear to be very little evidence in dogs we have to continue to draw from other fields – in one human study administration of oral Passiflora incarnata as a premedication reduces anxiety without inducing sedation.

Does it work? Again, it seems to help in humans but it’s not clear if that will extend to dogs.


Evidence for valerian is detailed here. The results are often conflicting; in addition, many studies (as with the other supplements) rely on owner or observer assessment which could be subjective and carry some bias including issues like the caregiver placebo effect. None of the studies have looked at physiological parameters such as heart rate, breathing rate and hormone concentrations. Instead, behavioural signs of stress were observed, signs such as lip licking, sighing, panting, trembling, recurrent yawning, circling and hyperactivity.

Does it work? It probably does something, but unfortunately, weak research methods haven’t proven it yet.

What can I do?

As you can see, supplements can be a very confusing area to investigate. Many of the supplements have real theoretical benefits and therefore it is certainly plausible that they do have some effect on our pets. At the moment, research is still weak and limited for many so although a supplement MAY work, it might also do nothing. This is why it is important to not use them as a sole intervention if your dog is experiencing anxiety, stress or distress. Always seek advice from your veterinary team and a veterinary behaviourist. Many are unlikely to do your dog any harm, so it could be something to try alongside other things.

Realistically many dogs with behavioural, emotional and anxiety disorders will actually benefit from a multimodal approach to their treatment and therapy. This will include working with a veterinary behaviourist who will work in a positive manner to support your pet, home and environment adaptations, enrichment, exercise changes, supplements and even the need for prescription medications in some cases.

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