Why We're Asking More Questions About mRNA Vaccines for Pets : Should You Be Cautious About mRNA Vaccines for Pets?
A Call for Research, Caution, and Responsible Stewardship
At Stokeshire, we believe that caring for our animals is about more than simply following trends or adopting the latest innovations. It’s about science, stewardship, and doing what’s right for the long-term health and happiness of the companions entrusted to us. When groundbreaking developments—like mRNA-based vaccines—enter the world of veterinary medicine, we take notice. We ask questions. We champion curiosity not because we are skeptical of science, but because we respect it deeply. True science invites exploration, discussion, and continuous learning.
This post sheds light on the promises and uncertainties surrounding mRNA vaccines for pets. It’s both a celebration of innovation and a thoughtful call for caution as we work together to ensure that advancements in veterinary medicine always serve the greater good.
The Potential of mRNA Vaccines in Veterinary Medicine
With the incredible strides mRNA technology has made in human medicine, it was only a matter of time before its application extended to our beloved pets. Following mRNA vaccine “successes” during the COVID-19 pandemic, the veterinary field has begun introducing these innovations to tackle diseases in dogs and cats.
For example, in 2024, Merck Animal Health launched the first mRNA-based vaccines for canine influenza (H3N2) and feline leukemia (FeLV). Vet professionals and researchers have highlighted four key potential benefits of mRNA vaccines for pets:
1. No Adjuvants or Preservatives
Unlike many traditional vaccines, mRNA vaccines like Nobivac® NXT are free from substances like adjuvants and preservatives, which are often added to enhance immune response. Avoiding these chemicals may reduce the risk of certain adverse reactions, making mRNA vaccines appealing for pets with sensitive systems.
2. Fast Adaptability to Mutating Diseases
One major advantage of mRNA vaccines is their speed. For rapidly mutating diseases like canine influenza, mRNA technology allows producers to update vaccines quickly, targeting new strains as they emerge. This adaptability could redefine how fast the veterinary field responds to outbreaks.
3. Strong Immune Responses
Early data suggests mRNA vaccines elicit both robust antibody and T-cell responses. For example, trials of an experimental mRNA rabies vaccine demonstrated higher, longer-lasting immunity with just one dose compared to traditional rabies vaccines.
4. Broad Expansion into Untapped Areas
Beyond currently targeted diseases like canine influenza or feline leukemia, research is forging ahead. mRNA vaccines for Lyme disease, rabies, and even some cancers are being explored, widening the scope of this powerful technology.
These impressive capabilities highlight the immense promise of mRNA vaccines. However, genuine progress also means asking the essential question, “What don’t we know yet?”
The Absence of Long-Term Data
The heart of Stokeshire’s care philosophy is one of balance—celebrating breakthroughs while carefully weighing their implications. Innovation and caution must work hand in hand. The reality is that mRNA vaccines, while promising, are still very new in veterinary care. That means we don’t yet have the full picture of how they may affect an animal for years to come.
Our concerns don’t stem from fear, but rather a deep sense of responsibility. Below, we highlight some of the key unknowns that require ongoing exploration.
1. Long-Term Health Impacts
While preliminary data shows promising short-term safety, we simply don’t have multi-year or generational studies on pets that have received mRNA vaccines. Will animals vaccinated with this new technology experience any impacts five or ten years down the road? Until we have long-term results, conclusions about full safety profiles must remain cautious.
2. Effects of Repeated Doses
Unlike traditional vaccines that might be boostered every three to five years, mRNA vaccines could require more frequent boosters depending on the duration of immunity they provide. How will a lifetime of repeated exposure to mRNA vaccines affect a pet's immune system? Could certain breeds or age groups respond differently over time? These questions deserve rigorous investigation.
3. Impact on Internal Systems
From the gut microbiome to the endocrine and reproductive systems, every aspect of a pet’s body plays a role in long-term health. While mRNA vaccines do not alter DNA, we don’t yet fully understand how they interact with the delicate systems of a growing or aging animal. Could immune stimulation from mRNA technology influence factors like fertility, development, or multi-generational health trends? For responsible breeders like Stokeshire, these gaps are significant.
4. Generational Questions
Particularly for breeding populations, there’s little data on how mRNA vaccines might affect offspring or future lineages. While existing studies show mRNA vaccines do not directly modify genetic material, a transparent effort to explore even subtle downstream effects is critical.
Science must set aside definitive conclusions until long-term studies can provide clarity. For now, it is our role to exercise thoughtful judgment and continue raising important questions.
Stokeshire’s Philosophy on Holistic Care
At Stokeshire, we look at every component of a pet’s health through the lens of whole-animal wellness, not just immediate solutions. From ethical breeding practices to preventive care, we believe in a tailored, balanced approach to raising resilient companion animals. Here’s how our values guide us in adopting—or questioning—new advancements:
Evidence-Driven Care
We prioritize proven interventions that demonstrate safety, efficacy, and alignment with the animal’s natural systems. If the data isn’t there, we proceed with caution.
Intentional Breeding Standards
By maintaining low inbreeding coefficients, comprehensive genetic testing, and thoughtful pairing, we give our puppies the best chance for robust health from day one.
Focus on Natural Resilience
Whether it’s through species-appropriate diets, microbiome health initiatives, or judicious vaccine schedules, we empower each animal’s natural ability to thrive while minimizing unnecessary interventions.
Transparency with Owners
Clients deserve full information about every health decision, from vaccines to daily care. We value collaboration with pet parents, arming them with knowledge to make thoughtful, informed choices for their animals.
mRNA Vaccines and Canine Cancer: What's the Real Story?
A recent human medical case has sparked conversations that are now echoing in the veterinary world. An elderly woman, long in remission from breast cancer, developed aggressive skin metastases shortly after receiving an mRNA vaccine booster. A biopsy found the vaccine-derived spike protein within the tumor cells, raising complex questions about the immune system and novel vaccine technologies.
This single case is not a conclusion, but a starting point for scientific inquiry. As mRNA technology finds its way into veterinary medicine, pet owners and veterinarians alike are asking important questions. Could something similar happen in dogs?
This post will explore the theoretical connections between mRNA technology and canine cancer. We will look at the science, separate fact from speculation, and discuss why rigorous research is the most important tool we have for ensuring the health and safety of our dogs.
The Human Case: A Catalyst for Questions
First, let's be clear about the details. In this specific case, researchers noted the presence of the vaccine's target protein (the spike protein) inside cancer cells. This suggested the vaccine components traveled beyond the injection site and were expressed in unexpected tissues. It's important to understand this is an isolated and highly unusual event.
For veterinary medicine, this case prompts us to consider a few theoretical possibilities:
Could veterinary mRNA vaccines distribute beyond the initial injection area in dogs?
Is it possible for the target proteins to be created inside other tissues, including pre-existing tumors?
How might this technology interact with a dog's unique immune system, especially concerning inflammation or tumor behavior?
These are not statements of fact, but essential questions that guide responsible scientific development.
Understanding Canine Cancer and the Immune System
Canine cancer is a complex field. Tumors in dogs, such as mammary tumors, hemangiosarcoma, and lymphoma, are often influenced by a combination of genetics, hormones, and immune system activity. The immune system's role is particularly interesting. It can be a powerful ally in fighting cancer, but its behavior can also be unpredictable.
Veterinarians are familiar with a phenomenon called a "tumor flare-up" following strong immune activation. This can happen after an infection, a traditional vaccine, or even immunotherapy. Usually, this is a good sign—it means the immune system is recognizing and attacking the cancer cells. The idea of an immune response that accelerates metastasis, as theorized in the human case, would be a highly atypical and unexpected outcome.
It is critical to state that there is no current evidence showing that any vaccine, including the developing mRNA ones, causes or accelerates cancer in dogs. Dogs and humans have different immune responses and metabolize substances differently. What happens in one species does not automatically translate to another.
A Look at Vaccines and Cancer in Pets
When discussing vaccines and cancer, it's easy to get confused. The only established (and very rare) link involves post-vaccinal sarcomas in cats, which are associated with specific adjuvanted killed-virus vaccines. This issue is not seen in dogs and is unrelated to mRNA technology.
Traditional canine vaccines have a long and successful history of preventing deadly infectious diseases with an excellent safety profile. They work by introducing a weakened or inactivated pathogen to teach the immune system how to fight it.
mRNA technology works differently. It delivers a set of instructions (messenger RNA) that teaches the body's cells to produce a specific protein from the pathogen. The immune system then learns to recognize and attack that protein. While several veterinary mRNA vaccines are in development for diseases like rabies, distemper, and Lyme disease, they remain largely experimental. The animal trials conducted so far have not shown any pro-cancer or metastatic effects.
The Path Forward: A Focus on Safety and Research
The lesson from this discussion is not that mRNA vaccines are dangerous for dogs. Instead, it’s a powerful reminder of the principles of good science and cautious innovation. Any new vaccine platform, whether for humans or animals, must undergo extensive testing.
For veterinary mRNA vaccines, this means researchers should prioritize:
Biodistribution Studies: These studies track where the vaccine components go in the body and how long they stay there. This helps ensure they work as intended without accumulating in unintended areas.
Long-Term Tumor Surveillance: Safety trials should include long-term monitoring for any changes in tumor development or behavior, especially in animals with pre-existing cancers.
Histopathological Analysis: If an unexpected health event, like rapid tumor growth, occurs after vaccination, detailed tissue analysis is crucial to understand what happened at a cellular level.
This level of scrutiny is standard for developing new veterinary medicines and ensures that any product that comes to market is both safe and effective.
A Balanced Takeaway for Pet Owners and Vets
As a pet owner or veterinarian, it's natural to have questions about new technologies. The evolving science around mRNA vaccines requires a balanced perspective, free from alarmism.
Right now, the conversation about mRNA vaccines and canine cancer is entirely theoretical. There is no data linking these vaccines to cancer in dogs. The benefits of vaccination in preventing widespread, fatal diseases are proven and substantial.
The key is to remain informed and trust the scientific process. Responsible researchers are asking the right questions to ensure the next generation of veterinary vaccines meets the highest safety standards. As mRNA technology continues to develop, we can expect transparent data and rigorous studies that will provide clear answers and guide its safe application in protecting our beloved animal companions.
Advocacy and Stewardship
Our stance on mRNA vaccines is not designed to criticize their development but to advocate for a careful, collaborative rollout. Veterinary advancements are most successful when every stakeholder—veterinarians, researchers, breeders, and owners—works together with transparency and shared goals of animal health.
Our Call to Action
To Medical Researchers:
Partner with breeders, pet families, and holistic experts to design studies that consider longevity, breed-specific responses, and the subtle complexities of animal lives.
To Breeders and Pet Owners:
Stay informed. Read data critically and consult trusted veterinarians before adopting new medical protocols.
To Regulators and Industry Leaders:
Transparency, robust safety profiles, and open dialogue are essential. Multi-year studies and robust post-licensure monitoring will help build public trust.
Our Promise
At Stokeshire, we make decisions not for convenience or expedience, but for the enduring happiness and health of every puppy we place. While mRNA vaccines may indeed prove to be a vital tool in veterinary care, they must meet the stringent standards of safety and long-term efficacy our animals deserve.
Conclusion
Science moves us forward, and love ensures we move thoughtfully. At Stokeshire, these principles work together as we consider the place of mRNA vaccines in caring for our animals. True progress means asking hard questions, waiting for comprehensive answers, and never wavering in our commitment to our pets’ lifelong well-being.
For our Stokeshire families, know this—we will continue to lead with care, caution, and an unwavering dedication to the values you trust. Together, we will ensure that every advancement builds a healthier, happier future for our companions.
References
American Animal Hospital Association (AAHA). (2025, April 3). RNA vaccines: The way of the future? Trends Magazine. https://www.aaha.org/trends-magazine/publications/rna-vaccines-the-way-of-the-future/
Embark Veterinary – Peterson, L. (2023, April 14). Why should breeders consider genetic COI in breeding decisions? Embark Vet Blog. https://embarkvet.com/resources/genetic-coi-dog-breeding/
Geesler, K. (2023, September 19). Penn Medicine develops mRNA vaccine against Lyme disease-causing bacteria. Penn Medicine News. https://www.pennmedicine.org/news/penn-medicine-develops-mrna-vaccine-against-lyme-disease
National Association of State Departments of Agriculture (NASDA). (2024, February 7). State departments of agriculture support farmer and rancher access to approved vaccine technologies [Press release]. https://www.nasda.org/state-departments-of-agriculture-support-farmer-and-rancher-access-to-approved-vaccine-technologies/
Sano, S., et al. (2025). A case of metastatic breast carcinoma to the skin expressing SARS-CoV-2 spike protein possibly derived from mRNA vaccine. Journal of Dermatological Science. https://doi.org/10.1016/j.jdermsci.2025.09.007
Squires, R. A., Crawford, C., Marcondes, M., & Whitley, N. (2024). 2024 guidelines for the vaccination of dogs and cats – compiled by the WSAVA Vaccination Guidelines Group. Journal of Small Animal Practice, 65(5), E1–E44. https://doi.org/10.1111/jsap.13718
The Kennel Club (UK). (n.d.). Inbreeding calculators (COIs). Retrieved August 6, 2025, from https://www.thekennelclub.org.uk/health-and-dog-care/health/getting-started-with-health-testing-and-screening/inbreeding-calculators/
Wang, Y., Yu, T., Zhang, S., Li, N., Zhao, J., Mi, L., ... & Miao, F. (2025). A lyophilized anti-rabies mRNA-LNP vaccine induces early and robust immune responses from a single-dose subcutaneous administration. Veterinary Microbiology, 307, 110612. https://doi.org/10.1016/j.vetmic.2025.110612
Xu, J., Becker, A. A. M. J., Luo, Y., Zhang, W., Ge, B., Leng, C., ... & Janssens, G. P. J. (2021). The fecal microbiota of dogs switching to a raw diet only partially converges to that of wolves. Frontiers in Microbiology, 12, Article 701439. https://doi.org/10.3389/fmicb.2021.701439