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
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