Pet Vaccines Informed Consent

Do vets in the U.S. give mRNA vaccines to pets?

Only in two cases right now:

• NOBIVAC® NXT Canine Flu H3N2 (for dog influenza)

• NOBIVAC® NXT FeLV (for feline leukemia virus in cats)
  These are described by Merck Animal Health as “RNA particle technology,” which is a self-amplifying RNA-style platform. They are marketed as preservative-free, thimerosal-free, and adjuvant-free.
  Every other common core pet vaccine in the U.S. (rabies, Bordetella/kennel cough, distemper combo, etc.) is currently killed virus, live-attenuated, or recombinant vector — not mRNA.

  Basically if it says “NXT” anywhere I would avoid it.

Are rabies vaccines for dogs and cats in the U.S. mRNA?

No. U.S.-licensed rabies vaccines like Defensor®/Vanguard® Rabies 3 Year (Zoetis), Rabvac® 3 (Elanco), and Nobivac® 3-Rabies (Merck) are traditional inactivated (“killed”) rabies virus vaccines, and they include preservatives such as thimerosal and/or gentamicin.
There is an RNA-platform rabies vaccine (Nobivac NXT Rabies) being sold in Canada, but that version is not licensed in the U.S. as of November 11, 2025.

What about Bordetella / kennel cough, is that mRNA?

No. The common Bordetella vaccines (for “kennel cough”) in the U.S. are either:

• Intranasal live-attenuated Bordetella bronchiseptica (e.g. Vanguard® B Intranasal, Zoetis), or

• Injectable inactivated antigen/extract (e.g. Bronchicine®, Zoetis).
  These use killed or weakened bacteria, not RNA. Some of these products list thimerosal as a preservative.

Why do some vaccines have thimerosal, gentamicin, etc.?

• Thimerosal is a mercury-containing preservative that’s been used for decades to keep multi-dose biologics from growing bacteria or fungi. It’s still listed in several veterinary rabies and Bordetella products. It was banned from use in human vaccines this year due to issues with safety.

• Gentamicin (an antibiotic) is often present in residual amounts from manufacturing to control contamination. It’s also listed on multiple rabies vaccine inserts.
  
  If an animal has a known allergy or you want to avoid those preservatives, you can ask for a specific product that is labeled “preservative-free,” “thimerosal-free,” or “adjuvant-free,” HOWEVER, the only preservative-free options for vaccination I could find online are on the mRNA platform (e.g. Nobivac NXT line).

What is an “adjuvant” and why does it matter?

An adjuvant is something added to a vaccine to make the immune system react more strongly to the antigen. Aluminum-based adjuvants and oil emulsions are common in traditional killed-virus or killed-bacteria vaccines. They are not always listed as “adjuvant” in casual marketing, but they’re in the full label/SDS. Some cat owners try to avoid adjuvanted injections because of concern about injection-site inflammation or sarcomas in cats; this is why “non-adjuvanted” feline vaccines like PUREVAX Rabies (canarypox vector) or the NXT FeLV (RNA particle; marketed as adjuvant-free) are heavily promoted.

Are these vaccines legally required?

• Rabies: In almost every U.S. state, rabies vaccination is legally required for dogs. Many counties also require it for cats, and some for ferrets. The specific product used just has to be a USDA-licensed rabies vaccine appropriate for that species and valid for 1-year or 3-year depending on label and local law. (Laws are state and county level; always verify locally.)

• Bordetella (Kennel Cough): Not required by law, but strongly required by boarding kennels, dog daycare, training classes, and many groomers.

• FeLV (Feline Leukemia): Strongly recommended for kittens and outdoor cats. Some rescues/shelters may require it for adoption, especially before group housing.

• Canine Influenza (CIV): Often required by boarding/daycare/training during local outbreaks, but not required by law.

If I don’t want my animal to receive an RNA-platform vaccine, what do I say at the clinic?

You can be very direct and still respectful. For example:

• For a dog: “I consent to rabies and distemper-parvo combo, but I do not consent to the NOBIVAC NXT Canine Flu H3N2 RNA-particle vaccine today. If you’re offering canine flu, I want a non-RNA killed-virus version or I’ll decline flu for now.”

• For a cat: “I consent to rabies, but for FeLV I do not consent to any Nobivac NXT or RNA-particle vaccine. If you only stock the RNA version, I’d like to skip FeLV today.”
  

  This tells them clearly: you are not refusing core legally required rabies, but you are directing which formulation they use for optional vaccines.

Do I have to accept combination vaccines?

Clinics like combos because it’s fewer pokes, faster workflow, and better compliance. But you can ask for single-antigen shots (for example, Bordetella by itself instead of the 5-way kennel combo that also includes parainfluenza, etc.). You can also ask to space vaccines out by a few weeks instead of doing everything in one visit. Most vets will work with you if you’re calm, specific, and sign their risk/benefit acknowledgment.

What about titer testing instead of re-vaccination?

Titers measure antibodies in the blood to see if the animal likely still has protective immunity, especially for core viral diseases like distemper and parvovirus in dogs, and panleukopenia in cats. Some holistic / integrative vets use titers to argue that revaccination is not needed yet.
Important: most U.S. jurisdictions do not accept titers in place of a current rabies certificate, so for rabies you’re still legally on the hook for the shot at the required interval even if a titer is positive.