Pet vaccination is the administration of a vaccine to a dog or cat to stimulate an immune response that protects against specific infectious diseases. Vaccines work by introducing a harmless form of a pathogen — killed, modified-live, or recombinant — so the immune system learns to recognize and fight it before the real disease exposure occurs. Vaccination is considered one of the most impactful preventive health measures available to pet owners, responsible for drastically reducing or eliminating once-common fatal diseases like canine parvovirus and feline panleukopenia.
Core vs. Non-Core Vaccines
Veterinary guidelines distinguish between core vaccines — recommended for every pet regardless of lifestyle — and non-core vaccines — recommended based on individual risk factors like geographic location, lifestyle, and exposure.
Core Vaccines for Dogs
- Rabies: Required by law in most US states. Fatal and transmissible to humans. Given at 12–16 weeks, boostered at 1 year, then every 1–3 years depending on vaccine type and local law.
- DHPP (Distemper, Hepatitis, Parvovirus, Parainfluenza): A combination vaccine protecting against four serious diseases. Given in a puppy series starting at 6–8 weeks, boostered every 3–4 weeks until 16 weeks, then at 1 year, then every 3 years.
Core Vaccines for Cats
- Rabies: Required by law in most jurisdictions, even for indoor cats. Given at 12–16 weeks, boostered at 1 year, then annually or every 3 years.
- FVRCP (Feline Viral Rhinotracheitis, Calicivirus, Panleukopenia): Protects against three common and serious feline diseases. Kitten series starting at 6–8 weeks, then every 3–4 weeks until 16–20 weeks, boostered at 1 year, then every 3 years.
Non-Core Vaccines
For dogs: Bordetella (kennel cough — required by most boarding and grooming facilities), Leptospirosis (for dogs exposed to wildlife or standing water), Lyme disease (in tick-endemic regions), and Canine Influenza (for dogs in high-density social settings). For cats: FeLV (Feline Leukemia Virus — strongly recommended for outdoor or multi-cat household cats), FIV, and Chlamydia. Your vet will recommend non-core vaccines based on your pet’s specific risk profile.
Puppy and Kitten Vaccination Schedule
The timing of puppy and kitten vaccines is carefully designed to provide protection as maternal antibodies (passed from mother to offspring) wane. Maternal antibodies protect newborns but also interfere with vaccine efficacy — this is why a series of vaccines spaced 3–4 weeks apart is needed, rather than a single shot.
A typical puppy schedule: 6–8 weeks (DHPP), 10–12 weeks (DHPP + Bordetella), 14–16 weeks (DHPP + Rabies + others as appropriate), 12–16 months (DHPP + Rabies booster). A typical kitten schedule: 6–8 weeks (FVRCP), 10–12 weeks (FVRCP + FeLV if recommended), 14–16 weeks (FVRCP + Rabies), 12 months (FVRCP + Rabies booster).
Adult Pet Booster Schedule
After the initial puppy/kitten series and 1-year boosters, most core vaccines shift to a 3-year schedule for adult pets, based on evidence that immunity lasts at least 3 years. Rabies vaccine intervals are governed by local law — some jurisdictions mandate annual rabies vaccination regardless of the vaccine’s licensed duration. Non-core vaccines like Bordetella and Leptospirosis are typically given annually.
Titer testing — a blood test measuring the level of antibodies against specific diseases — can be used to assess whether immunity is still present without automatically re-vaccinating. Many pet owners and vets use titer tests to make more individualized decisions about booster timing, particularly for the DHPP and FVRCP components. Titer tests cannot substitute for Rabies vaccination where it is legally required.
Vaccine Side Effects
Most pets tolerate vaccines well. Common, expected reactions include mild soreness at the injection site, low-grade lethargy, and reduced appetite for 24–48 hours. These are signs of a normal immune response and resolve without treatment.
Rare but serious reactions include allergic hypersensitivity (hives, facial swelling, vomiting within 30–60 minutes of vaccination) and, very rarely, anaphylaxis. Cats are at low risk for injection-site sarcomas (tumors) — modern protocols use specific injection sites and rotate locations to minimize this risk and allow early detection. If your pet shows difficulty breathing, severe swelling, or collapse after vaccination, contact your vet or emergency clinic immediately.