| Core vaccines for dogs | Rabies, Distemper, Parvovirus, Adenovirus (Hepatitis) (AAHA Canine Vaccination Guidelines) |
| Core vaccines for cats | Rabies, Feline Herpesvirus-1, Calicivirus, Panleukopenia (AAFP Feline Vaccination Guidelines) |
| Puppy/kitten series start age | 6–8 weeks, given every 3–4 weeks until ~16 weeks (AAHA / AAFP guidelines) |
| Rabies vaccine legal status | Legally required in most U.S. states for dogs; many states include cats (Varies by state and locality) |
| FeLV classification for kittens | Considered core for all kittens by AAFP (AAFP Feline Vaccination Guidelines) |
| Booster frequency (core, post-series) | 1-year booster, then every 1–3 years depending on vaccine (AAHA / AAFP guidelines; local law may differ for rabies) |
Core vs. Non-Core: The Essential Distinction
When your vet talks about vaccines, the most important category to understand is core vs. non-core. The American Animal Hospital Association (AAHA) and the American Association of Feline Practitioners (AAFP) use these terms in their published vaccination guidelines to help vets and owners make consistent, evidence-based decisions.
Core vaccine
A vaccine recommended for every dog or cat regardless of lifestyle. Core vaccines protect against diseases that are widespread, serious, or pose a public health risk — such as rabies, distemper, and parvovirus.
Non-core vaccine
A vaccine recommended selectively based on a pet's individual risk factors, such as geographic location, lifestyle, or level of contact with other animals. Non-core doesn't mean unimportant — it means not universally necessary.
Maternal antibodies
Protective proteins passed from a mother to her offspring through colostrum (first milk). These antibodies offer temporary protection but also interfere with early vaccine effectiveness, which is why puppy and kitten vaccines are given in a series.
Zoonotic disease
A disease that can be transmitted between animals and humans. Rabies and leptospirosis are examples of zoonotic diseases, which is one reason vaccination against them carries public health weight beyond the individual pet.
Duration of immunity
How long a vaccine is scientifically shown to maintain protective immunity after administration. Some vaccines have documented 3-year duration of immunity, reducing the need for annual boosters.
FVRCP / DA2PP
Common combination vaccine abbreviations. FVRCP covers feline viral rhinotracheitis, calicivirus, and panleukopenia. DA2PP covers distemper, adenovirus type 2, parvovirus, and parainfluenza in dogs. These combos simplify vaccine administration.
Core vaccines are recommended for every dog or cat, regardless of lifestyle, location, or living situation. They protect against diseases that are highly contagious, pose serious health risks, or carry public health implications (like rabies). Non-core vaccines are recommended selectively — based on where your pet lives, what activities they do, and what risks they're actually exposed to.
Neither category is optional in the sense of being unimportant. The distinction is about universal necessity vs. individualized risk. Your vet is the right person to help you map non-core vaccines to your specific pet's life. See our guide to what happens at a routine vet visit for context on how these conversations typically unfold.
Core Vaccines by Species
Here's a practical reference for what falls under the core category for dogs and cats in the United States.
Dogs
- Rabies — Required by law in most U.S. states. Fatal to both animals and humans if untreated. Initial vaccine typically given between 12–16 weeks, with boosters at 1 year and then every 1–3 years depending on product and local law.
- Distemper — Highly contagious viral illness affecting the respiratory, gastrointestinal, and nervous systems. Spread through airborne exposure.
- Parvovirus — Potentially fatal, especially in puppies. Extremely hardy virus that can survive in the environment for months.
- Adenovirus (Hepatitis) — Protects against infectious canine hepatitis. Often combined in the DA2PP or DHPP combo vaccine alongside distemper and parvo.
Cats
- Rabies — Core for cats just as for dogs, and legally required in many jurisdictions regardless of whether a cat lives indoors.
- Feline Herpesvirus-1 (FHV-1) and Feline Calicivirus (FCV) — Both cause upper respiratory disease. Typically combined with panleukopenia in the FVRCP vaccine.
- Feline Panleukopenia (FPV) — Often called feline distemper. Severe, frequently fatal in kittens. Highly resistant in the environment.
| Core vaccines for dogs | Rabies, Distemper, Parvovirus, Adenovirus (Hepatitis) (AAHA Canine Vaccination Guidelines) |
| Core vaccines for cats | Rabies, Feline Herpesvirus-1, Calicivirus, Panleukopenia (AAFP Feline Vaccination Guidelines) |
| Puppy/kitten series start age | 6–8 weeks, given every 3–4 weeks until ~16 weeks (AAHA / AAFP guidelines) |
| Rabies vaccine legal status | Legally required in most U.S. states for dogs; many states include cats (Varies by state and locality) |
| FeLV classification for kittens | Considered core for all kittens by AAFP (AAFP Feline Vaccination Guidelines) |
| Booster frequency (core, post-series) | 1-year booster, then every 1–3 years depending on vaccine (AAHA / AAFP guidelines; local law may differ for rabies) |
Non-Core Vaccines and Who Needs Them
Non-core vaccines are not second-tier — they're simply targeted. Whether your vet recommends them depends on a realistic assessment of your pet's exposure risk.
For Dogs
- Bordetella (Kennel Cough) — Often required by boarding facilities and groomers. Recommended for any dog with regular contact with other dogs.
- Leptospirosis — A bacterial infection spread through water or soil contaminated by wildlife urine. Relevant for dogs that hike, swim, or live in areas with wildlife exposure. Also a zoonotic risk to humans.
- Lyme Disease — Recommended in tick-endemic regions or for dogs spending time outdoors in wooded or grassy areas.
- Canine Influenza (H3N2 / H3N8) — Relevant in areas with documented outbreaks, or for dogs in high-contact settings.
For Cats
- Feline Leukemia Virus (FeLV) — AAFP considers this core for all kittens and recommends it for cats with any outdoor access or contact with cats of unknown status. Spread through close contact with infected cats.
- Feline Immunodeficiency Virus (FIV) — Risk is higher in cats that go outdoors and may fight with other cats.
- Chlamydophila felis and Bordetella — More relevant in multi-cat households or shelter environments.
If you're building out a full health plan for a new pet, our new pet owner health checklist covers vaccines alongside microchipping, parasite prevention, and more.
How Timing and Boosters Work
Puppies and kittens receive their first vaccines in a series — typically starting around 6–8 weeks of age — because maternal antibodies (passed through the mother's milk) can interfere with vaccine effectiveness early on. Giving vaccines in intervals allows immunity to build as those maternal antibodies wane.
A standard puppy series for core vaccines runs every 3–4 weeks until around 16 weeks of age. Kittens follow a similar pattern. After the initial puppy or kitten series, most core vaccines transition to a booster at 1 year, and then every 1–3 years depending on the specific vaccine and your vet's assessment.
It's worth noting that "annual vaccines" is a somewhat outdated blanket phrase. Many core vaccines now carry 3-year label claims backed by duration-of-immunity studies. Rabies vaccine intervals are also governed by your local or state law, not just label claims — so what applies to a neighbor's dog may not apply to yours if you're in a different county or state.
Vaccine records matter more than many owners realize — boarding facilities, groomers, dog parks, and airlines all commonly require them. Maintaining an organized record for each pet is a simple habit that pays off. Learn more about what a full wellness visit covers in our annual vet visit breakdown.
This article is for general informational purposes only and is not a substitute for professional veterinary advice. Vaccine recommendations can vary based on your pet's health history, local disease prevalence, and applicable laws. Always consult a licensed veterinarian to determine the right vaccination plan for your individual pet.