Dog vaccination schedule: what the dates mean and what to track

That is a question for the veterinarian who examines your dog, but the structure of the answer is worth understanding, because it is the same structure almost everywhere.

Canine vaccines are sorted into two groups. Core vaccines are recommended broadly for dogs. Non-core — risk-based or lifestyle-based — are recommended for an individual dog when their circumstances warrant it. AAHA defines non-core vaccines as those recommended for some dogs based on lifestyle, geographic location and exposure risk. That is the key idea: the second group is decided per animal, not per species.

Globally (WSAVA 2024)

WSAVA's 2024 guidelines identify the globally relevant canine core vaccines as those protecting against canine distemper virus (CDV), canine adenovirus (CAV) and canine parvovirus (CPV). Two more are conditional rather than universal:

• Rabies — core where rabies is endemic.
• Leptospirosis — to be considered core in countries or regions where canine leptospirosis is endemic, the implicated serogroups are known, and suitable vaccines covering the relevant serovars are available.

In the United States (AAHA)

AAHA's canine vaccination guidelines, which cover US and North American practice and US-licensed vaccines, place distemper, adenovirus, parvovirus, leptospirosis and rabies in its core recommendations, with parainfluenza shown as "+/−" alongside the distemper/adenovirus/parvovirus combination — a conditional entry rather than an unqualified core recommendation. AAHA notes that the guideline was updated in 2024 to make leptospirosis a recommended core vaccine for all dogs.

Not all boosters are annual, and treating "yearly shots" as a rule is a common oversimplification. Intervals differ by vaccine, and AAHA's US guidance shows both patterns side by side: its DAP combination schedule carries 3-year subsequent boosters, while its current leptospirosis schedule carries annual subsequent boosters. Two core vaccines in the same guideline, on different cycles.

For the core CDV/CAV/CPV components specifically, WSAVA's 2024 guidelines describe revaccination at 3 years of age and thereafter no more frequently than every 3 years, following whichever post-series option was used. AAHA's US guidance reaches the long interval by a different route: a combination dose within 1 year after the final dose of the initial series, then subsequent boosters at 3-year intervals.

The practical consequence for a record is that "when is my dog due" is usually several questions, not one. Recording which vaccine each date belongs to is what keeps them separable.

Because reputable guidelines are written for different places, and they say so. This is one common reason an owner can find two trustworthy sources that appear to disagree — and it is usually scope, not error.

Leptospirosis is the clearest example. WSAVA, writing globally, treats it as a vaccine to consider core where the disease is endemic, the implicated serogroups are known, and suitable vaccines are available. AAHA, writing for US practice where those conditions largely hold, classifies it as core for all dogs following its 2024 update. Both are current. They differ because the question "is this disease a meaningful local risk, and is a suitable vaccine available?" has different answers in different countries.

Post-series timing is a second example. WSAVA offers a choice — serological testing at least four weeks after the final puppy dose, or an additional core dose at or shortly after 26 weeks; AAHA's US wording places a combination dose within 1 year of the final initial-series dose. 🔴 Do not split the difference. Averaging two guidelines produces a schedule that neither body recommends.

The practical conclusion is simple, and it is the same one your veterinary practice will give you: the operative schedule is the one your veterinarian has documented for your dog, based on where you live, the products available there, and your dog as an individual.

All of these can legitimately change what is recommended and when, which is why two healthy dogs on the same street can have different schedules:

• Age and life stage — a puppy mid-series, a young adult and an older dog are not on the same plan
• Vaccination history — what was given, when, and whether the record is complete
• Individual health — existing conditions and medications are part of the assessment
• Lifestyle and exposure — boarding, daycare, grooming, group classes, shows, working dogs, hunting, contact with wildlife or standing water
• Geographic disease risk — which diseases are actually present where the dog lives and travels
• The vaccine product — different products carry different labelled intervals
• Local veterinary and legal requirements — especially rabies

Merck's framing of non-core vaccines as risk-assessed captures the general principle: the second group of vaccines exists precisely because these factors differ between animals.

You resolve it with your veterinary practice — you do not decide the catch-up yourself. "Overdue" is not one situation. What the correct next step is depends on which vaccine it is, how much time has passed, what the dog has had before, whether the earlier record is complete, and the product being used. Those variables are exactly why the answer is a conversation rather than a rule.

Do not assume a lapsed schedule means restarting the whole series, and do not assume it means a single catch-up dose either. The appropriate next step is vaccine-specific and depends on the previous record, elapsed time, product and veterinary guidance.

There is a concrete reason the practice is the right place to resolve it: AAHA's guidance is that overdue vaccination should be worked out using vaccine-specific guidance from the manufacturer. That information sits with the product and the clinician, not with the owner or with a website.

What you can usefully do is call, say which vaccine and which date, and bring the record. A practice can usually resolve an overdue date quickly when it can see what came before.

The vaccination record itself, in whatever form you have it; the dates and products if they are written down; any known conditions and current medications; any previous reaction to a vaccine, however mild it seemed; and an honest description of your dog's lifestyle — where they go, who they mix with, whether they board, and where you travel with them. That last one is what the risk-based half of the schedule is built from, and only you have it.

Our guide to preparing information for a vet visit sets out the wider checklist, and Patter and your veterinarian covers where an app's records stop and a practice's begin.

• Cat vaccination schedule — the same questions for cats, where the core list and the indoor-cat question both work differently.
• How to prepare information for a vet visit — the wider set of information worth bringing.
• What to track when your pet seems different — recording an observation well, including after a vaccination.