01/04/2025
Bovine Serum Albumin (BSA) is an ingredient in many vaccines, functioning as an antigen. Studies have found that higher concentrations of BSA has been linked to a higher risk of vaccine adverse effects. Studies have also shown that combination vaccines, particularly those combining modified live and inactivated (typically Lepto) pathogens, have higher concentrations of BSA. Check out the differences in the header graphic. These measurements are averaged amongst various manufacturers in the attached study.
Because BSA can cause allergic reactions in humans the World Health Organization (WHO) has set a guidance of 50 ng (0.05ug)or less residual BSA per vaccine dose. This is significantly less than what is present in animal vaccines.
Its important to also note, in addition to multivalent vaccines (which include Lepto) having higher BSA concentrations, Lepto vaccines themselves have been reported to carry a higher risk of adverse events, regardless of BSA content. Surface proteins of leptospirosis (LPS lipopolysaccharides antigens) used to make vaccines, have been linked to hypersensitivity and immune dysfunction.
This article is not intended to dissuade people from immunising their pet. It is to raise awareness that there are ways to lower adverse event risk. Highlighting the difference in antigenic load between monovalent and multivalent vaccines being one. Also the awareness that Leptospirosis vaccines (particularly Lepto 4) may carry higher risks and should be diligently considered, alongside research into environmental and lifestyle risk of infection for the individual animal.
Taking all into consideration it is clear that, at the very least, vaccines should not be overused and/or unnecessarily. Titre testing for existing immunity, avoiding multiple-dosing and manufacturer selection are all things to consider. Those with smaller breeds may also want to discuss with their veterinarian the possibility of lower or half-dosing, as some consider this to be safer and still effective (although many vets at this time discourage this)
Having considered conversations with your vet about vaccines, whilst educating yourself on the risks (of both vaccine and infection) and ways to lower said risk, I believe is essential to the wellness of your pet.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7112531/ #!po=20.9677
https://pubmed.ncbi.nlm.nih.gov/15734545/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7112591/ #!po=40.3846
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2327198/