7 Factors Affecting Immunity

Immunity – a word we hear so often in the health and diet industry. The basis of health all around. It can be very much a ‘rabbit hole’ subject, because the further you look into it, the deeper you research. It can be a confusing topic at best, so here at My Pet Nutritionist, we have put together this handy guide on things that can affect immunity.

What is Immunity?

Immunity is the ability to be resistant to a pathogen or infectious disease. Immunity can be gained naturally (through careful socialisation), by exposure to the pathogen, or through the use of vaccinations.‍

There are various mechanisms of immunity, which we will briefly outline below:

Active Immunity

This is what is happening when the dog is exposed to a pathogen. The active immune system is the fastest acting system and is the body’s first response to the presence of a pathogen. In the presence of a pathogen, the B-Lymphocytes create and release antibodies.

Passive Immunity

This is the immunity passed on to an individual instead of being created by their body. In dogs we call this Maternally Derived Antibodies (MDA). MDA is passed onto the puppies from the mother and is vital to health in the early weeks. It usually wanes between 10 and 16 weeks of age, unless interrupted by vaccination. MDA is passed onto the puppies through the placenta, and through the mothers milk. If a puppy is hand reared, he/she may require extra caution than those who drink mothers milk.

Innate (also called non-specific) Immunity

This is immunity and defence systems your dog is born with. Barriers like skin, the gastro-intestinal tract, eyelashes etc all help keep pathogens out of the body which is why gut health is so very important – at least 70% of your immune system is in the gut! Defence systems like mucosal layers, saliva, stomach acid etc are also part of the innate immune system. Another immune response included as part of the innate immune system is inflammation – this often acts as a marker to pathogens so they can be destroyed.

Adaptive (or Acquired) Immunity

This is the immunity gained following seroconversion of vaccinations, or through natural build up of immunity. The Adaptive Immune System can be separated into two mechanisms.‍

  • Humoral (antibody mediated) immunity
This primarily involves B-Lymphocytes. During a humoral immune response, when an antigen is detected, with the help of T Helper Lymphocytes, the B Cells go through a differentiation process, which produces Memory B Cells and Effector B Cells, which are both specific to the B Cell they were differentiated from, and therefore are specifically shaped to combat a specific antigen/pathogen. This is the most common immune response, especially following successful vaccination. Titre Tests pick up these antibodies.‍

  • Cellular, or cell-mediated immunity
This involves another type of cell – T-Cells. When T-Cells differentiate, they become T-Killer Cells which attach to and engulf antigens. Allergic responses and autoimmune conditions are part of the cell-mediated adaptive immune system.

So, let’s discuss some of the factors which affect immunity.


Genetics play a large role in immune responses. If a dog comes from lines of ‘breeding stock’ affected by genetic health issues which affect the immune system, it is very likely they will also carry the genes.
There are many ‘pathways’ in the genome (all of the body’s DNA), which contribute to various bodily functions. Studies around genetics and the link with the immune system mainly focus on the Toll Pathway, which in vertebrate animals, is all about inflammation. Inflammation occurs in response to infection or virus. The Toll pathway helps to regulate inflammation in the body by triggering the release of antimicrobial peptides in response to challenge. When the pathway is downregulated by SUMOylation (a protein which prepares cells for transcription, DNA binding, and replication), it misfires; this can lead to greater inflammatory response.

Findings Here

The domestication of dogs has also contributed to genetic immune function issues – going from hunting to having food served to them, going from a natural diet to, in many cases, a commercially prepared diet are both factors which over time, alter genetics. Survival of the fittest, and selective breeding will bring these altered genes out in litters, which then continue for future generations. In many breeds, the gene pool is very small, which also leads to larger affects on the immune system.‍

Findings Here

Pregnancy and Birth

During pregnancy, many changes occur in the mother’s body. Hormones strengthen and change, the body physically changes, milk production begins, and the immune system takes a beating in order to produce a healthy litter, at the same time as keeping healthy herself.‍

During pregnancy, the immune priorities are changed. It’s a common misconception that during pregnancy there is a time of immunosuppression; what actually happens, is the innate immune system strengthens, in order to provide the puppies with great physical barriers, but there is a reduction in the adaptive immune system, particularly later in the pregnancy, which is why many bitches suffer with itching or yeast toward the end of the pregnancy, and shortly after giving birth.‍

Finding Here

During birthing, the neonatal puppy’s innate immune system comes into full force, as it goes from being protected in the womb/uterus, to being completely open to the environment, including various pathogens. The Maternally Derived Antibodies will now be viable too, to help protect the puppy against viruses in the environment.

Findings Here

If the MDA is interrupted by early vaccination, this can leave the puppy more vulnerable to disease, so it’s incredibly important to understand when the best time to vaccinate is, if using vaccines for your puppy. That leads us nicely on to toxin exposure.

Toxin Exposure

There are so many toxins our pets are exposed to on a regular basis, both through some veterinary pharmaceuticals, and through household products in the environment. These toxins can have a largely detrimental effect on the dog’s immunity.


While we are not against vaccinations here at My Pet Nutritionist, we feel it is incredibly important to vaccinate wisely, and minimally. There is so much research available, such as the works of Dr Ronald Schultz, and directly on the datasheet from the manufacturers of the vaccines.

Adjuvants used in the vaccines, including heavy metals, are recognised as foreign bodies, which when inserted into the individual with strands of the virus, are then removed by the immune system, along with the viral particles. Unfortunately the exposure to toxins in the vaccines, affects the adaptive immune system, and can cause brief immunosuppression, along with other health problems.

Over vaccination is ever so popular, which unfortunately is harming our pets. A minimal vaccine protocol, and regular titre testing is the more responsible, and healthier approach! You can read more on vaccines in the blogs below!

Vaccinosis: Damage Vaccinations Can Cause Your Pet
Everything You Need to Know About Vaccinations

Flea and worm treatment

Another commonly used assortment of products among the pet community, is pest control. These days, there is a huge range of products on the market, with a variety of methods of administration to the pet.

Oral flea and worm products have been linked to seizures, ataxia, death, and all sorts of other health issues. One of the isooxazoline class products is banned by the European Medicines Agency, while the FDA have put out official warnings on others.

Spot on flea and worm treatments not only can cause seizures, but they often cause major skin irritations, including burns to the area of application. ‍

Chemical wormers damage the gut, a little like paint stripper. ‍

All these products damage the gut, which in turn damages the immune system, and weakens the dog’s immunity. If you use these products, consider switching to natural alternatives, running regular wormcounts, and working on the gut to ensure it is in the best condition it can be in following likely damage from these products. ‍

Findings Here

Household cleaning/laundry/fragrance products

Even those labelled as ‘pet safe’ (meaning they’re unlikely to kill your pet), can cause major health complications, including gut damage. Try to use natural products where possible! ‍

Many household fragrance products contain Volatile Organic Compounds (VOCs), which are linked with allergies, breathing and airway complications, particularly at the time of birth as they interact negatively with the developing immune system. ‍

Findings Here


The Microbiome‍

The microbiome is all the microbes in the gut, including good and bad. A healthy microbiota is so important for all aspects of health, so when there is an unbalance in the gut, and the microbiome is comprised of more harmful microbes than good (whether it’s bad bacteria, yeast overgrowth, or parasitical), the immune system is maimed. ‍

An imbalance in the gut, causes gut damage, which in turn leads to leaky gut. Sadly, a leaky gut is an easy pathway for the onset of many health issues, including autoimmune conditions, as the body sees leaked particles as foreign bodies, and produces a histamine, and inflammatory response. ‍

Around 90% of today’s chronic illness is silently caused by an imbalanced gut. Keeping the microbiome healthy, through good diet, correct supplementation and regular parasite checks is key to keeping immunity strong! ‍


As with everything, diet is always a big part of general health! What we feed our pets has a huge effect on the immune system. The vast majority of the immune system is located in the gut, so it’s super important to keep the dog’s gut health in check. Feeding a processed diet, high in non-biologically appropriate ingredients, and often contaminated with mycotoxins, aflatoxins, storage mites and glyphosate will be detrimental to gut health, and therefore detrimental to immunity. ‍

Ensure you feed a fresh diet, whether that is raw or cooked. You may wish to work on the gut with a mucilage such as Marshmallow Root or Slippery Elm, and include a good probiotic in your regime. ‍

Gut Guardian


Stress is a huge factor in immune health. Stress can be heavily linked to immunosuppression. Stressors within the body can include everything from psychological stress to physical stress, chemical/hormonal stress or infectious stress. ‍

When our pet’s bodies go through any form of stress, the gut integrity is damaged. Adaptive immunity is affected by stress. One theory is that the body uses it’s resources elsewhere when the body is under any form of stress. Another theory is that neuroendocrine system regulates the immune system in order to reduce the risk of autoimmune responses. ‍

Findings Here
Findings Here


The final factor we will discuss is infection. Whether it’s bacterial or viral, infection does affect the immune system. ‍


When a dog becomes unwell with a bacterial illness, such as campylobacter, sepsis, or other internal infections, the gut is often damaged; much like a vicious circle, because poor gut integrity contributes to infection, and infection worsens gut integrity. Antibiotics are often used to clear infections from the body, which not only remove the bad bacteria causing the infection, but they also destroy the good bacteria in the microbiome. When the gut integrity is damaged, the immune system is weakened. ‍

Adding probiotics to your dog’s regime may be very beneficial, by recolonising the gut, and helping to keep the immune system strong when on antibiotics or suffering from infection. ‍

Findings Here
Findings Here


When a dog is exposed to a virus, particularly one it is not immune to, the immune system is put to work, to establish what the viral particle is, and how to rid the body of it. This can put strain on the immune system, and temporarily cause a slight dip in immune response. When gradually exposed to the virus in question however, natural immunity can be built! This will not shock the immune system, but instead encourage it to create an immune response to the virus which will then be stored in memory cells as part of the Adaptive immune system. ‍

Findings Here

If you are struggling to keep your pet’s immune system strong, or need guidance on moving away from any of the chemical treatments mentioned in this blog, please don’t hesitate to contact us for a consultation! ‍

Team MPN x

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