The gut-brain connection: 4 ways to boost your pets gut microbiota

Picture of Dr. Else Verbeek
Dr. Else Verbeek

Dog behaviour scientist and consultant.

There are trillions of bacteria living in an animal’s gut. You’ve probably heard that these gut microbes are important for health and digestion, and that it is important to feed your pet a healthy and balanced diet to support the ‘good ‘ bacteria. But did you know that gut microbes are also very important for an animal’s mental well-being? Gut microbes communicate with the brain and so influence brain function and behaviour. 


Picture of a grey cat
Skitterphoto from
How? We’re still figuring that out, but so far it seems that gut microbes produce active substances when they ferment fibers in the animal’s gut, and these can travel to the brain though the blood stream. 

Gut microbes also produce neuro-transmitters (the chemicals that the nerve cells use to signal each other). The gut microbiota actually produces more serotonin – an important neuro-transmitter involved in the regulation of emotions – than the brain itself.

Gut microbes directly communicate with the central nervous system through the vagus nerve and so influence how your animal feels and behaves.

The gut-brain
connection regulates the emotional well-being of animals.

Stress and the gut microbiota

An unbalanced gut microbiota can be problematic, and cause trouble beyond an upset stomach. In labs across the word, scientists raised animals (rodents) that had no gut-microbiota at all. It turned out that when these rodents experienced something scary, they showed an abnormally large hormonal stress response. The behaviour of these germ-free animals was also markedly different from animals with a normal gut microbiota.

These studies showed that the gut microbiota is critical for regulating the hormonal and behavioural responses to stress.

Research in pigs has shown that the gut microbiota and microbial metabolites are linked to tail biting. Tail biting is an abnormal behaviour which causes pain and psychological stress. Pigs that bit the tails of other pigs had a higher relative abundance of Firmicute bacteria, and a lower amount of Short Chain Fatty Acids in their faeces, which are the messengers that gut microbes send to the brain to alter behaviour.

In another study, pigs were supplemented with Lactobacillus probiotics – which are live beneficial bacteria – from birth until weaning. Then the piglets’ behavioural reactions towards a scary sound (play-back of a loud dog bark) were tested. It was found that the control group increased vigilance behaviour, but the probiotics group did not, suggesting that the probiotics reduced anxiety.

Many other studies have shown that an unbalanced gut micobiota is linked to depression and anxiety disorders in both humans and animals.


The gut microbiota
influences how well animals cope with stress



So how can you support your pets gut microbiota to reduce stre

Four ways to boost the gut microbiota 

  1. Feed the right type and amount of fiber. Check what is right for the species, oats may be a good option. 
  2. Feed a varied and balanced diet. Don’t get just a random cheap bag of food from the supermarket,
    make sure it is appropriately formulated by a specialist (check
    with your vet or nutritional adviser).
  3. Don’t obsess about hygiene. Bacteria live in the dirt. Excessive washing and disinfecting kills
    even the good bacteria. For example, the development of the gut
    microbiota is compromised in pigs living in excessively clean
    indoor environments.
  4. Supplement with pre- and/or pro-biotics. Prebiotics provide the right substrates for beneficial microbes
    (certain types of fiber) and probiotics are living beneficial


  1. The microbiome-gut-brain axis: from bowel to behavior
  2. Establishment
    of normal gut microbiota is compromised under excessive
    hygiene conditions
  3. The Gut-Brain Axis in Neurodegenerative Diseases and Relevance of the Canine Model: A Review
  4. Influence of the microbiota-gut-brain axis on behavior and welfare in farm animals: A review
  5. The gut microbiota and microbial metabolites are associated with tail biting in pigs
  6. Supplementation of Lactobacillus early in life alters attention bias to threat in piglets 

Did you enjoy this post and want to stay updated about the latest dog behaviour science? Enter your email address is the subscription box below:

Want to know more about the science of dog behaviour and welfare?

Sign up now and receive regular tips and insights about dog behaviour and welfare in your inbox.

Unsubscribe at any time.

Dr Else Verbeek en witte hond