Updated July 26, 2026·5 minper WSAVAAnswer — in the first paragraph ↓
MISSED BOOSTER
If a dog missed a booster of the combo vaccine, the series is not started from scratch: a single dose is usually enough, even after more than three years. Leptospirosis is the exception — after a gap of over 18 months the two-dose course is repeated. For puppies the rule is different: the last dose of the series must land at 16 weeks or later.
01What happens after a missed shot
What was missed
Time passed
What is usually done
Combo shot (DHP)
over 3 years
one dose, the series is not restarted
Leptospirosis
over 18 months
course again: 2 doses, 3–4 weeks apart
No shots or records lost
—
2 DHP doses, then every 3 years
Rabies
—
set by national law, check with the clinic
The combo shot is not restarted because immune memory after it lasts a long time. The World Small Animal Veterinary Association (WSAVA) puts protection from modified live vaccines at 7–9 years and more, while the three-year booster interval is a practical recommendation with a safety margin. So a single dose after a long gap simply puts the dog back on schedule.
02Leptospirosis is the one exception
Protection against leptospirosis lasts about a year, which is why the shot is repeated annually. If the gap stretched beyond 18 months, one dose is not enough — the course is repeated: two doses 3–4 weeks apart. The same applies if the dog never had the leptospirosis shot at all. What else belongs in the adult schedule is covered in adult dog vaccinations.
03If the puppy series slipped
With puppies the count is about age, not about misses. The series is not squeezed: at least 2 weeks between doses, usually 3–4. And the key point — the final dose of the combo vaccine has to land at 16 weeks or later, otherwise maternal antibodies can cancel out the shot. If the start was late and the puppy is already 10–12 weeks old, the series is shorter: two doses, the last after 16 weeks. The full timeline is in the puppy vaccination schedule.
Platera keeps vaccination dates at hand
The last dose, the next due date and an early reminder.
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04Frequently asked
Is being a month late dangerous?
It depends on the shot. The combo vaccine has a wide safety margin, so a month does not break the schedule. Leptospirosis protection is designed to last about a year, so that one is better not postponed. Rabies should not slip either, because the timing is set by law. Your vet will work out the plan from the dates in the record book.
What if the rabies shot is overdue?
The rabies interval is set by national law, not only by the product: some places require a yearly shot even with a three-year vaccine. So an overdue date is sorted out at the clinic, together with what the record book says. If a trip abroad is coming up, check the timing early — border rules are stricter.
What if a puppy missed the second dose?
What counts is age, not the missed dates. At least two weeks have to pass between doses, and the last dose of the combo vaccine must land at 16 weeks or later. If the puppy is already older than 16 weeks, two doses 3–4 weeks apart are usually enough. The exact plan is set by the vet based on the puppy’s age.
Can a missed shot be combined with deworming?
Yes. There is no mandatory gap between a deworming treatment and a vaccination: they can even be done on the same day. The “10–14 days before the shot” rule is a habit rather than a guideline requirement, and there is a separate article about it. If in doubt, ask the clinic when you book.
MISSED BOOSTER
