Puppy worming schedule by age — a UK week-by-week guide

Quick answer. The UK standard puppy worming schedule is first dose at 4 weeks of age, then every 2 weeks until 12 weeks old, then monthly until 6 months, then move to the adult 3-monthly schedule. The reason for the short interval is transplacental transmission — almost every puppy is born already infected with Toxocara canis larvae from the dam, regardless of how recently she was wormed. Two-weekly dosing catches each generation of maturing worms before they reach egg-laying adulthood. Worm the dam at the same time as the puppies. Biheldon is dosed at 1 tablet per 10 kg body weight, so most puppies need a quarter or half tablet — see the dosing chart.

Puppy worming is the most schedule-intensive period of a dog’s life — five doses in the first three months, another three to four through to six months. The reason is biology, not paranoia: Toxocara canis has a transmission route in dogs that’s unique among UK pet parasites, and it requires the tight schedule below to control. This guide walks through the schedule week-by-week, why it works the way it does, and how to handle the common edge cases (rescued puppies, missed doses, very small breeds).

Why puppies need worming every 2 weeks

The dominant intestinal worm in UK puppies is Toxocara canis, the dog roundworm. Two transmission routes matter:

1. Transplacental transmission — encysted larvae in the dam’s tissues reactivate during the last trimester of pregnancy and cross the placenta into the puppies. By birth, almost all puppies carry a Toxocara canis burden. This happens regardless of how recently the dam was wormed, because the encysted larvae are in tissues outside the gut where standard wormers don’t reach.

2. Trans-mammary transmission — larvae continue to be shed in the dam’s milk for several weeks after birth. Even a puppy that was somehow born clear would be re-infected through nursing.

The result: every puppy you take on (whether bred at home, from a registered breeder, from a rescue, or from a shelter) should be assumed to carry Toxocara and require worming from 4 weeks of age. The 2-weekly interval through the early life stage catches each new wave of larvae before they mature into egg-laying adults that shed back into the environment.

The UK standard schedule

This is the ESCCAP UK published recommendation and aligns with the MSD Veterinary Manual standard.

Worm the dam on the same days as the puppies to prevent her from continuously re-shedding larvae through milk. The dam returns to her normal 3-monthly schedule once the puppies are weaned (around 8 weeks).

Dosing puppies — most need a quarter or half tablet

Puppies at 4 weeks of age typically weigh 1–4 kg depending on breed:

By 12 weeks, most puppies have moved into the 5–10 kg or 10–20 kg range and may need a full tablet or two. Reweigh the puppy at each dose and adjust — fast-growing breeds (Labradors, Retrievers, German Shepherds) can jump weight bands meaningfully between doses.

The full Biheldon dosing chart is on the product page. Biheldon’s scored tablets split cleanly into halves and quarters for accurate small-puppy dosing.

What about puppies under 4 weeks?

The standard tablet wormers (Biheldon, Drontal, Milbemax) are licensed from 4 weeks of age. For very young puppies — those identified as needing worming earlier than 4 weeks for clinical reasons (heavy visible roundworm burden, failure to thrive) — your vet will typically use:

• Panacur Puppy Liquid Suspension (2.5%) — licensed from 2 weeks of age, dosed by millilitre

Do not improvise dosing for very young puppies. This is a vet-led situation.

”I just rehomed a puppy and the worming history is unclear”

This is a common scenario, particularly with rescue puppies. The safe assumption: assume the puppy has not been wormed recently, give a dose immediately, then start the 2-weekly schedule from there.

Some practical guidance:

• 8-week-old rescue with no records? Treat as a 4-week-old puppy in terms of worming — dose now, dose again in 2 weeks, and continue the schedule. The extra early doses do no harm.
• 12-week-old rescue with no records? Same approach — dose now, dose every 2 weeks until they’ve had 3 doses, then move to monthly to 6 months.
• Adult dog rescue? Standard adult schedule from the day you get them — see the adult worming frequency guide.

A faecal egg count two weeks after the first dose confirms the treatment worked — useful if the puppy looks heavily-burdened.

Signs of a heavy worm burden in puppies

A puppy with a clinically significant Toxocara burden often shows:

• Pot-bellied appearance — disproportionate to the puppy’s frame
• Visible adult roundworms in stool (pale, spaghetti-like, 5–15 cm) or in vomit
• Failure to thrive — slower weight gain than littermates, dull coat
• Persistent diarrhoea that doesn’t have an obvious dietary cause
• Mucus in stool

If you see these alongside the planned worming, give the next dose on schedule and tell your vet — they may want to confirm with a faecal egg count and may suggest a follow-up dose 2 weeks later to confirm clearance.

Lungworm — not part of the standard puppy schedule

The standard puppy worming schedule covers intestinal parasites — Toxocara canis (roundworm), Ancylostoma and Uncinaria (hookworm), and some tapeworm exposure. It does not cover lungworm.

Lungworm (Angiostrongylus vasorum) becomes a concern from around 8–12 weeks when puppies start exploring gardens and outdoor areas where slugs and snails are present. In lungworm-endemic UK regions (south-east England, midlands, south Wales, increasingly Scotland), your vet may recommend starting a monthly milbemycin or moxidectin preventive product alongside the standard puppy schedule.

See the lungworm in dogs guide for the full picture, and the Biheldon vs Milbemax comparison for the product choice.

Coordinating with the vaccination schedule

The standard UK puppy vaccination schedule (first vaccine at 6–8 weeks, second at 10–12 weeks) overlaps with the worming schedule. Practical guidance:

• Worming and vaccination on the same day is generally fine for healthy puppies. The vaccine works on the immune system; the wormer works on the gut. No clinical interaction.
• If your puppy is unwell on vaccination day (mild GI upset, off food), your vet may postpone one or both. Follow their advice over the calendar.
• If your vet specifically asks you to stagger, follow that advice — sometimes individual cases warrant separating events for diagnostic clarity.

For most puppies, doing worming on the same days as vaccinations is the simplest approach — it builds a routine and means fewer separate vet visits.

When to call the vet

For most healthy puppies, the schedule above plus the standard vaccination plan plus a few routine check-ups is the whole picture. Call your vet additionally if:

• The puppy is showing clinical signs of heavy worm burden (pot-belly, failure to thrive, persistent diarrhoea) and the next dose is more than a week away
• The puppy is vomiting persistently in the 24 hours after a dose
• You see blood in stool at any point
• The puppy is under 4 weeks and needs worming for any reason
• You have a multi-puppy household (a litter you’re raising) and want to coordinate dam-and-puppies dosing properly

Where Biheldon fits in the puppy schedule

For a single Labrador-sized puppy from 4 weeks to 6 months, Biheldon usage roughly looks like:

• 4 weeks (2 kg): ¼ tablet
• 6 weeks (4 kg): ½ tablet
• 8 weeks (7 kg): 1 tablet (rehoming dose)
• 10 weeks (10 kg): 1 tablet
• 12 weeks (13 kg): 2 tablets
• 16 weeks (17 kg): 2 tablets
• 20 weeks (21 kg): 2 tablets — last “monthly” dose
• 6 months onwards: 2½ tablets every 3 months as an adult

That’s roughly 11 tablets across the first 6 months, plus the dam’s same-day doses, plus the puppy’s continuing adult schedule. A single 30-tablet Biheldon box covers a small litter through the puppy schedule with plenty to spare for the dam and the puppies’ first year as adults.

The bottom line

The UK standard puppy worming schedule is first dose at 4 weeks, every 2 weeks to 12 weeks, monthly to 6 months, then move to the adult 3-monthly schedule. Worm the dam on the same days as the puppies through weaning. Biheldon’s scored tablets cover the small-puppy quarter- and half-tablet doses cleanly.

For rescue puppies with unknown history, assume they haven’t been wormed recently and start the schedule from today. For very young puppies under 4 weeks, use Panacur Liquid Suspension (vet-led). For lungworm-endemic areas, add a monthly macrocyclic-lactone product from around 8–12 weeks of age.

See Biheldon’s dosing chart by puppy weight, the pillar guide on how often to worm a dog for the adult schedule once your puppy is past 6 months, and the worming side effects guide for what to expect after a dose.

Tags: #dogs#puppies#schedule#esccap