How gut health affects immunity

Dr. Ailsa Rutherford
5 min readSep 3, 2022


Photo by Izabelly Marques on Unsplash

Recently, the relationships between gut health and general well-being have become better understood and more relevant in medical care for people and animals. We know that in humans, 70–80% of the body’s immune cells exist within the digestive system, and we believe it is very similar to our furry friends. In particular, the immune system requires optimal nutrition to function correctly, keeping illness and diseases at bay.

Good gut health is defined as a good balance and variety of microorganisms to help break down food, absorb energy, remove toxins and waste, destroy pathogens, and maintain immune homeostasis. The digestive system, or gut, functions with the help of its microbiome, or community of microorganisms living together in a specific environment. These bacteria, fungi, and bacteria have crucial roles within the gut and immune systems.

The immune system will develop dysregulation when the gut’s healthy bacteria and other microorganisms are disturbed or destroyed. This disruption can cause small-scale issues such as allergy flare-ups, food intolerances, or more severe problems, such as inflammatory bowel disease, poor or extended healing, and autoimmune disorders.

Improving your Pet’s Gut Health and Immunity

The gut, and therefore, the immune system, can be easily affected by diet, medications, illnesses, antimicrobial cleaners, and stress. Frequent vomiting, diarrhea, dehydration, constipation, stomach ache, loss of appetite or abdominal pain, and bloating are all signs of poor gut health. Likewise, recurrent infections, poor growth, post-vaccination illnesses, lethargy, and skin diseases indicate a weak immune system.

Microbiome Gut Health Test

If possible, starting with a microbiome gut health test can provide helpful information for what your pet needs going forward. The test works by sequencing the bacterial DNA from a fecal sample, revealing the bacteria present and their concentration.

By comparing your pet’s results to those of a similar, healthy animal, your veterinarian can help guide you through the following steps.

This testing is an essential step if your pet’s gut health seems to be declining, even if they previously had good health. Many pets quickly develop a healthy mix of bacteria thanks to the microbes they encounter during birth and through nursing with their mother.

Biologically Appropriate Diet

All animals need a nutrient-dense diet similar to what they evolved to digest for optimal health. There are options for supplementing a kibble diet with fresh whole foods or creating home-prepared meats from scratch. Transitioning to a whole, semi-raw, or raw diet may help. Raw food diets have been controversial over the last decade, so before deciding for or against them, speak to your vet and do plenty of research to determine what’s best for you and your pet.

Regardless of the options you choose for your pet, remember that the absorption and digestibility of nutrients are fundamental. A secondary benefit of a biologically appropriate diet is promoting good oral health. Remember that changing your pet’s diet should always be done gradually and in conjunction with the advice and supervision of your veterinarian.

Supplement Foundations

Supplementing your pet’s diet can be a convenient and beneficial way to support good gut health and a robust immune system. Probiotics have long since been hailed as a significant part of digestive health. Their work promotes a balanced gut microflora to aid in better digestion, creating vitamins, and suppressing harmful bacteria. Though they have a lesser-known reputation, prebiotics (supplements that contain fuel for good bacteria) can play a crucial role in digestive functions.

Antioxidants reduce and prevent damage generated by free radicals, which are unstable atoms caused by diet, medicines, pollution, and stress. Essential fatty acids such as omega-3 and omega-6 are necessary to maintain the function of cell membranes and receptors and develop various hormones.

Natural Supplements

Hemp seed oil: Hemp seed oil is extracted from industrial hemp plant seeds through a cold-pressing process to supplement the diets of humans and animals. Hemp seed is a natural source of nutrient-dense prebiotics and high levels of essential fatty acids with anti-inflammatory properties. These characteristics make hemp seeds and hemp seed oil a great supplement for gut health and overall immunity.

At BUDDYPET, we recommend Marley for adult dogs and Milly for seniors.

For more information on how hemp can help, please read Hemp, Nature’s Superfood for Digestive Health.

Spirulina: A type of blue-green algae consumed by humans and animals for its anti-inflammatory, anti-bacterial, anti-viral, antioxidant, and immunostimulatory qualities. Spirulina has a very high protein content and is rich in vitamins, minerals, and essential fatty acids, making it another excellent option for supporting your pet’s immune system and gut health.

Turmeric: This common spice has been long loved for its anti-inflammatory, anti-viral, anti-bacterial, anti-fungi, antioxidant, and anti-cancer properties. Its active ingredient, curcumin, has been used in both therapeutic and clinical settings and has impressive results compared to conventional drugs.

The Relationships Between Dental Health, Gut Health, and Overall Immunity

Did you know that in addition to the immune system, dental health is also directly affected by gut health? We already know that the microbiome in the gut is vital for digestive processes, removing toxins and harmful bacteria, and supporting the immune system. Similarly, a microbiome in the mouth consists primarily of bacteria and maintains oral health when adequately balanced.

The mouth has the second largest and most diverse microbiome in humans, following the gut and harbouring over 700 species of bacteria. Some of the same bacteria are found in the mouth and the gut, though they may not behave the same in both locations. The bacteria can cause both oral and systemic diseases when the oral equilibrium becomes unbalanced.

Poor oral health can lead to localised issues such as gum disease, loose or painful teeth, oral infections, and the need for surgical extractions. It can also lead to systemic disease if toxins or bacteria entering the mouth can take hold rather than be fought off by the oral microbiome.

For animals with a healthy immune system, the average amount of bacteria and harmful toxins entering through the oral route does not pose much of a threat. The genuinely vulnerable will be animals with poor dental and gut health and a weak immune system. Inadequate diet, unmanaged medical conditions, and poor welfare can all lead to poorly balanced microbiomes in both the mouth and gut, leading to severe health conditions ambushing an already impaired immune system.

For more insights on how to support or improve your pet’s digestive health, please read Ten Ways to Improve Your Dog’s Health Naturally.



Dr. Ailsa Rutherford

Senior practicing veterinarian. Member of the Australia and New Zealand College of Veterinary Surgeons in Emergency. Head of Animal Health at Buddy Pet P/L.