How to Feed My Pet

Vaccinations and parasite control

Dogs & cats2 weeks – 16 weeks·Sources checked September 13, 2026
This is general information, not veterinary advice, and it cannot diagnose your animal. Very young puppies and kittens deteriorate quickly — when something looks wrong, contact a veterinarian rather than waiting to see if it resolves. Medical disclaimer

The question behind most confusion here is: why so many injections? Antibodies from the mother protect a newborn early on — and the same antibodies interfere with vaccination. They fade at a different time in every individual, so a single early injection cannot reliably be the one that works. The series exists to catch the moment the animal can finally respond.

How we label our evidence

  • Source-supportedStated directly in the cited institutional publication.
  • Our editorial guidanceA conservative reading of the evidence applied to a caregiver decision. Not a validated clinical protocol.
  • Evidence gapWe could not verify this in our approved sources, so we have not invented a number.

The core viral series

For DAP in puppies (distemper, adenovirus, parvovirus) and FVRCP in kittens (panleukopenia, herpesvirus-1, calicivirus), WSAVA 2024 recommends:

  • Start at 6–8 weeks
  • Repeat every 2–4 weeks
  • Final dose of the initial series at 16 weeks or older — high-risk circumstances can justify continuing to 18–20 weeks
  • Revaccinate at or shortly after 26 weeks, which catches animals that never responded earlier

A schedule of 8, 12, and 16 weeks is one illustration of a four-week interval. It is an example, not a prescription — shelter protocols, local disease pressure, and the specific vaccine product all change it.

Source-supported
WSAVA and AAHA do not say identical things, and we have kept both rather than blending them. For the follow-up dose after the initial puppy series, AAHA describes one within a year; WSAVA points to around 26 weeks. When someone quotes a schedule at you, it is worth knowing which guideline they are quoting.

Puppies

Core viral: AAHA specifies at least three combination doses between 6 and 16 weeks, 2–4 weeks apart, followed by a dose within one year of the initial series.

Leptospirosis: AAHA's 2024 update designates it core for all dogs — two doses 2–4 weeks apart starting at 12 weeks, then annual boosters. WSAVA treats it as core where the disease is endemic, relevant serogroups are known, and suitable vaccines exist. AAHA's is a regional recommendation, not a global rule.

Bordetella, influenza, Lyme: depend on exposure and location.

Rabies: timing and legal requirements vary by jurisdiction. Confirm with a veterinarian where you live — this is the one item on the page where the law, not just the medicine, decides.

Kittens

FVRCP: AAHA/AAFP 2020 — start no earlier than 6 weeks, repeat every 3–4 weeks until 16–20 weeks, and consider revaccination with the injectable combination at six months.

FeLV: core for cats under one year. Start as early as 8 weeks, two doses 3–4 weeks apart, with FeLV antigen testing beforehand. Revaccinate 12 months after the initial series, then reassess based on exposure. WSAVA specifies FeLV as core for young cats in regions where FeLV-associated disease is endemic.

Rabies: follows product labelling and local law.

Two things people get wrong: that indoor kittens need no vaccines, and that the six-month FVRCP visit also completes FeLV and rabies. These have separate indications and separate schedules.

Internal parasites

Merck's roundworm control example starts earlier than most people expect — at two weeks — and treats the nursing mother at the same time.

Merck roundworm-control example — not a universal schedule for every parasite or product
SpeciesSchedule
PuppiesFrom 2 weeks, every 2 weeks until 3 months, then monthly until 6 months
KittensFrom 2 weeks, every 2 weeks through 12 weeks, then monthly until 6 months

Watch for: poor growth, a pot belly, worms in vomit or faeces, diarrhoea, pale gums, or dark stools.

Source-supported
A negative faecal test does not exclude parasites. Shedding is intermittent, and severe hookworm disease can occur in a young puppy before eggs are detectable at all. One clear result is weaker evidence than it feels like.

Flea and tick products

There is no single starting age that applies to every flea or tick medicine. Before using anything, check: species it is licensed for, active ingredients, formulation, minimum labelled age, minimum labelled weight, the animal's current weight, and what it has already had.

Evidence gap
We could not verify a comprehensive international minimum-age and weight table across products, so we will not publish one — and you should be sceptical of any article that says "all flea treatments are safe at eight weeks." Read the actual label for the actual product, and ask your veterinarian.

Call now for triage

Heavy flea infestation in a kitten can cause anaemia. Do not wait until it reaches an assumed medication age — get advice. Pale gums, weakness, or breathing difficulty means emergency assessment.

After a vaccination

What the action labels mean

Emergency now —
contact an emergency veterinary service and arrange immediate assessment. Do not wait for the next scheduled feed or weigh-in.
Call now for triage —
telephone the veterinary service when you notice the sign. The veterinarian decides how quickly the animal needs to be seen.
Contact today —
get in touch when you notice the issue to agree on a time. This does not mean waiting until evening.

Emergency now

Breathing difficulty or collapse after vaccination.

Call now for triage

Hives, facial swelling, marked itching, or vomiting within hours of vaccination — contact the vaccinating clinic. Also call for persistent appetite loss or lethargy rather than assuming it is a harmless reaction.

Kittens

Injection-site lumps — the "3-2-1" rule. Have a lump investigated if it persists for 3 months, exceeds 2 cm, or is still enlarging 1 month after injection. Any one of the three qualifies.

This concerns examination and biopsy — it is not an emergency designation for every small lump after a shot.

Common misconceptions

  • "One vaccination means fully protected." Maternal antibody interference is exactly why the series exists.
  • "A negative stool test excludes parasites." See above.
  • "Kittens must always start deworming at three weeks." Merck's example starts at two.

Sources