L-Tryptophan for dogs

Updated 19 April 2024
Read time: 9 mins
article author
Written by Corinne Homer

We pride ourselves on our “Good Mood Food’ and amongst all the goodness and nutritional benefits within our products - L-tryptophan is one of the biggest game-changers.

It’s a nifty amino acid found in some natural foods, and it works wonders in stabilising and calming a dog’s mood. We are big L-tryptophan fans!

If it sounds too good to be true, read on as we explain the uses of L-tryptophan for dogs, and how you can get its calming, mood-boosting powers into their diet.

What is L-tryptophan?

L-tryptophan is a smart amino acid that’s found in some protein-rich foods such as turkey, salmon and eggs; and eating it is linked to the release of serotonin - the ‘happy hormone’.


How does L-tryptophan work?

The smart thing about L-tryptophan is it’s a precursor to the release of serotonin, a neurotransmitter in the brain that causes ‘happiness’. Specifically, serotonin has a calming and positive effect on wellbeing, as well as regulating sleep and appetite (major elements of being in a good mood).

So when a dog eats foods containing L-tryptophan such as turkey or chicken, it’s converted into serotonin in a dog’s brain, leading them to feel calmer and more relaxed. This brain-friendly amino acid is big proof of the impact of the gut-brain axis, i.e. how important nutrition is to a dog’s wellbeing.


How does serotonin affect dogs?

Serotonin is known as ‘the happy hormone’. Basically it’s a mood stabiliser which regulates a dog’s sense of calmness, wellbeing, and even sleep cycles and appetite.

For this reason, foods that activate serotonin are great for dogs who suffer from hyperactivity, aggression or anxiety. It’s also handy for times in which your dog feels considerable stress, or gets ‘triggered’ by what’s around them.


Why is L-tryptophan essential?

Dogs’ brains have their own natural levels of serotonin, but conversely, L-tryptophan (which enables more serotonin), isn’t produced in a dog’s body. So, for your pooch to get their maximum healthy dose of serotonin, their diet should contain lots of delicious doggo ‘good-mood food’ containing L-tryptophan.

What’s more, L-tryptophan is more than just a means to reduce anxiety in a dog - it has lots of uses for a dog’s nutritional needs. As a building block of protein, it helps to build and maintain muscle and connective tissue, it boosts melatonin (vital for sleep regulation), it contributes to a strong immune system, and it activates vitamin B12, important for a dog’s healthy skin and coat.


Tryptophan deficiency in dogs

What if we skip the good-mood foods? Well, a deficiency in L-tryptophan can have all kinds of negative effects on a dog’s body. In general, their immunity will lower, strength in their muscles will weaken, and they could appear anxious, hyperactive, agitated, or develop a generally low mood.

Cats as well as dogs need L-tryptophan to stay healthy and regulated - it’s a vital amino acid for a lot of mammals.


A bird's eye view of a dog bowl, including turkey, peas, and sweet potato

What are the benefits of L-tryptophan for dogs?

We’ve covered how L-tryptophan facilitates the release of serotonin, now here are the beneficial ways this can present in your pooch:

Less anxiety & agitation

The release of serotonin reduces anxiety and hyperactivity. Anxiety in dogs might present as digestive issues, trembling, fear, inability to sleep or settle, or a sensitivity to stimuli. They might ‘play up’ at certain times of day, such as before bed time or when visitors arrive. All of these symptoms could lessen by feeding them a healthy diet, rich in L-tryptophan foods and calming dog treats.

Helps with abnormal behaviours

Some pooches develop abnormal behaviour due to their mood or anxiety - excessive chewing, scratching, crying, or distressed rituals such as hiding or digging. Some pooches simply can’t sleep at regular times. L-tryptophan dense foods can help reduce or eliminate these behaviours, alongside behavioural training. 

Regulates the appetite

A pooch who eats too much or doesn’t eat enough can develop a more routine appetite with L-tryptophan, as serotonin helps with hunger regulation.

Better temperature regulation

Your pooch’s body will be better at keeping cool in warm weather, and retaining heat in cold temperatures, with the right amount of L-tryptophan in their diet.

Promotes healthy sleep

Serotonin is a vital hormone for sleep regulation, so your pooch will get sleepier at the same time of day and wake up on time, too. There’s nothing better than a pooch with a regular sleep schedule!

Easier pain management

The release of serotonin in the body goes some way in helping a pooch deal with pain, as it relaxes the mind and promotes a sense of calm and wellbeing. Try it after your dog has had an operation or suffered an injury, for instance, or if they suffer chronic pain.

A white Chihuahua dog, stretching next to a pot of our Hemp Chewies, against a pale pink background

Is L-tryptophan safe for dogs?

L-tryptophan is definitely safe for dogs - it’s an essential amino acid that has big benefits on a dog’s body and mind. That said, an excess of any ingredient or supplement isn’t recommended; and it must be fed to your pooch as part of a balanced diet.

Tryptophan foods for dogs

L-tryptophan is found in lots of natural foods that dogs find delicious, so it’s easy to boost your pooch’s intake. Just include foods such as these in their diet:

  • Turkey
  • Chicken
  • Salmon
  • Beef
  • Cooked eggs
  • Cheddar cheese (as a treat!)


How to safely give L-tryptophan to your dog

Your pooch can get the mood-boosting benefits of L-tryptophan from a nutritious, well-balanced diet containing whole foods such as turkey, salmon, eggs (and others listed above).

You could try dog food with turkey, and other calming food products for dogs which often contains ingredients rich in L-tryptophan. For the best results, any tryptophan-rich foods will be served to your dog alongside vegetables, fruits and carbohydrates packed with vitamins and minerals.

Give these calming foods to your dogs at times you think they’ll benefit from it most, considering when they might be feeling particularly jumpy or anxious. This could be at night time, when visitors are due, or when they’re going to the vet or groomers, for instance.


L-tryptophan supplements for dogs

If for some reason it’s not possible to give your pooch whole foods such as turkey or eggs (if they have allergies or tummy issues), you could try L-tryptophan supplements for dogs.

Take special care to administer the correct dosage - it should be described on the pack according to your dog’s size and age, but if not, consult with your vet to be sure. L-tryptophan supplements might come as tablets, or as a powder or liquid to serve alongside your dog’s regular food.


Precautions and side effects

As with any new food or health supplement, you’ll need to keep an eye on your dog for any side effects of L-tryptophan, and be cautious when giving it to your pooch for the first time.


Is my dog allergic to L-tryptophan?

Though it’s unlikely your pooch will have an allergy to the L-tryptophan found in natural foods, they may react to the food itself, or to the quality of the supplements.


Discontinue use if you notice your dog showing any of the following allergic reactions after eating food or supplements containing L-tryptophan: Vomiting or diarrhoea Reddening or swelling of the skin Hives Breathing difficulties Lethargy


Can dogs overdose on L-Tryptophan?

It’s rare, but a dog can get too much L-tryptophan, which is why it’s so integral to feed them a well-rounded diet. This should be full of healthy whole foods, providing them with a balance of nutrients, vitamins and minerals. Too much of one food, or mixing supplements with other medications, could cause an overdose of L-tryptophan, leading to dangerous side effects in your pooch.


Serotonin syndrome in dogs

A potential risk of too much L-tryptophan is ‘serotonin syndrome’, a condition where a pooch gets too much serotonin. This is rare, but could happen if your dog eats too much of one food, overdoses on L-tryptophan supplements, or is taking other medications which could interact and cause unwanted side effects.


Signs of serotonin syndrome in dogs to watch out for:

  • Agitation, restlessness
  • Increased body temperature
  • Fast heart rate
  • Trembling
  • Dilated pupils
  • They’re disorientated, lack of coordination
  • Vomiting and/or diarrhoea

If you note any of the above symptoms, get your pooch to a vet immediately.


Will L-tryptophan make my dog drowsy?

No - it shouldn’t do this. L-tryptophan is supposed to have calming effects and may make your dog feel more relaxed.


This is different to drowsiness, where a dog seems ‘out of it’ or like they’re too disorientated or tired to carry out their usual routine. If you note drowsiness in your pooch after they’ve eaten foods or supplements with L-tryptophan, it could be worth calling your vet, as they may have eaten too much or be having a bad reaction to it.


The ‘Turkey Sleepiness’ myth

You may have heard a rumour about how turkey - a nutritious, lean protein that has lots of natural L-tryptophan - induces sleepiness in whoever eats it (dogs included). This isn’t true, either.

This belief may have come from the notion that turkey is served with all the trimmings at Christmas and Thanksgiving meals, which often induces lethargy and sleepiness after eating! The truth is, turkey doesn’t cause a sense of sleepiness, in humans or dogs, more than any other food.

To be clear, at its most effective, L-tryptophan will instil a sense of relaxation and calm in your pooch due to the boost of serotonin - it shouldn’t cause drowsiness or lethargy.

 Some products from our Calming Range, against a bright purple background

How can I get L-tryptophan into my dog’s diet?

If you’re looking for L-tryptophan rich foods that dogs love, or other healthy treats to give your dog a sense of calmness, why not try the following from the Pooch & Mutt range?


Now you’re clued up on the scientific smartness of L-tryptophan, are you ready to add this super mood-booster into your dogs’ meals? Try the irresistible snacks and meals from our Calming range - packed with natural anti-anxiety ingredients for a satisfied pooch that’s relaxed, healthy and happy.


Is CBD more effective than L-Tryptophan?

Though it isn’t yet officially recognised by veterinary boards in the UK, lots of dog owners are starting to realise the potential benefits of CBD for dogs. Both L-tryptophan and CBD are known for their relaxing effects which make them good natural mood stabilisers.

They also interact with the body in different ways - CBD works with the endocannabinoid system (ECS) in the body, and L-tryptophan with the neurotransmitter serotonin, meaning they may work well in combination when carefully managed.

It’s very important to discuss this with a vet if you’d like to try both these natural relaxants on your pooch - as whether it’s safe can be very dependent on your dog’s age, breed and health condition. If you’re intrigued about CBD, we’ve explained more in our article on CBD products for dogs.

L-theanine vs L-tryptophan for dogs?

L-theanine is another mood stabiliser that can be given to dogs, and it’s different to L-tryptophan.

Mainly, L-theanine is found in foods such as tea leaves, and is linked to the release of gamma-aminobutyric acid (GABA), another neurotransmitter which has a calming effect on the brain. As L-theanine comes from tea, it’s harder to give this to your pooch in a munchable food format, like you can with L-tryptophan.

For this reason it often comes in the form of an anxiety supplement for dogs, such as a powder or tablet (though you could add a few spoonfuls of warm tea to your pooch’s food, if you preferred). Again, a combination of these two supplements could have a powerful mood-boosting impact on your dog - just chat your plans over with your vet first, to be safe.

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