My practice recently decided to transition from the adjuvanted killed rabies vaccine for cats to the non-adjuvanted recombinant rabies vaccine for cats. Now you may be wondering, what’s the difference and why does it even matter what type of vaccine a cat gets? There are some important points to understand in the difference between the vaccine types, how vaccine choice can affect our feline friends, and why choosing non-adjuvanted vaccines is believed to be the safer option in vaccine choices for cats. Read on to become a more informed and knowledgeable feline ally!
What Is A Vaccine And How Does It Work?
We all understand the importance of vaccines in the prevention of highly contagious and/or potentially fatal diseases and illnesses. Vaccines work by stimulating or “training” your immune system to create antibodies that fight against viruses or bacteria. They induce a fast and effective response for protection. For cats, there are multiple vaccine types on the market, including adjuvanted and nonadjuvanted vaccines.
- Adjuvanted Vaccines: Contain additives that stimulate the immune system and increase the effectiveness of the vaccine. Adjuvants are often used in “killed” vaccines, which contain inactivated but antigenically intact viruses or organisms, a natural or synthetic antigen derived from those viruses or organisms, or DNA that can encode such an antigen.
- Nonadjuvanted Vaccines: Do not contain additional additives. They rely on the antigen alone (a portion of the pathogen that triggers the immune response) to stimulate immunity.
Why Do We Have To Think About This For Cats?
Though fairly rare, cats can develop a unique type of cancer that occurs at injection sites. These are called injection-site fibrosarcomas, an invasive and often life-threatening cancer. Although there are still some unknowns over the exact cause of injection-site fibrosarcomas it is believed that a localized chronic inflammatory reaction initiates malignant transformation of mesenchymal cells and that this process may have some genetic basis. While any injection, vaccine or otherwise, could potentially be associated with fibrosarcomas, studies suggest that adjuvants in vaccines, particularly killed adjuvanted vaccines, are highly linked to injection-site fibrosarcomas in cats. Incidence reports vary, but the risk for development of an injection-site fibrosarcoma could be 1 in every 10,000 cats.
How Do We Reduce The Risk of Injection-Site Fibrosarcomas?
The general consensus to reduce the risk of injection-site fibrosarcomas is to increase the duration between vaccines whenever possible and remove the adjuvant from the vaccine. The PUREVAX vaccines were developed using state-of-the-art technology specifically for cats and kittens, with these considerations in mind. The vaccine delivers everything needed to induce immunity without any unnecessary adjuvants. PUREVAX vaccines use only a portion of the pathogenic organism, meaning there is no potential for reversion to virulence. My hospital is now carrying the 1-year PUREVAX Rabies vaccine for kittens and previously unvaccinated adult cats and the 3-year PUREVAX Rabies vaccine for previously vaccinated adult cats. Due to the delicate manufacturing process, there is typically a higher cost associated with these safer non-adjuvanted vaccines, but I believe these vaccines promote the best medicine and the safest protocol for my feline patients.
On a side note, there has also been a movement to steer away from administering vaccines in the scruff or between the shoulder blades of cats and kittens. The recommendations are to aim for vaccine administration in the lower limbs or even tail for cats and kittens. The reasoning for this is that in the unfortunate event that a fibrosarcoma does develop, there is a more successful chance for removal on an extremity compared to in the center of the back. And while it is normal to sometimes feel a small lump in the area of vaccine administration immediately after vaccination, some general rules to follow are that any lump at a vaccination site should be seen by a veterinarian if it remains present 3 months after vaccination, is larger than 2cm in diameter, or is increasing in size 1 month after vaccination.
As always, talk to your veterinarian about making the best choices and decisions for your own furry little companions, and give them all extra chin scratches and forehead kisses for me!