The Corgi Puppy Deworming Schedule, Week by Week

Part of our complete guide series on parasite prevention for Corgi breeders. This article is a deep dive into puppy-stage deworming — for the full breeding-cycle picture, including what happens before and during pregnancy, see our pillar guide,

The Corgi Breeder's Complete Guide to Parasite Prevention.

 

Why Puppies Are Dewormed on a Fixed Schedule — Not Just When They Look Sick

If you're new to breeding, the first thing worth understanding is this: puppy deworming isn't reactive. You don't wait for a pot-bellied puppy or a bout of diarrhea before you start treating. You deworm on a fixed schedule, starting at two weeks of age, regardless of whether any puppy in the litter shows a single symptom.

 

The reason comes down to biology, not caution for caution's sake. Roundworm larvae can lie dormant in a dam's tissue for years, invisible to fecal testing, and reactivate under the hormonal changes of pregnancy. Those larvae can cross the placenta before birth (transplacental transmission) and pass through milk during nursing (transmammary transmission). Because of this, veterinarians generally treat it as a near-certainty that most puppies carry at least some roundworm burden at birth — even from a dam who tested completely clean before breeding, and even in a spotlessly clean whelping setup. The infection route, in many cases, has nothing to do with environmental hygiene at all.

 

That's why the schedule below exists as a program, not a single event — and why sticking to it matters even when a litter looks perfectly healthy.

 

A quick but important note before we go further: this article intentionally does not include specific drug names or dosing amounts. Dosing depends on your puppies' individual weights, your vet's product choice, and your region's parasite prevalence, and getting it wrong in either direction (too little, or an inappropriate product for a very young puppy) carries real risk. Treat everything below as a framework to bring to your vet, not a substitute for their guidance.

 

The Standard Framework: 2, 4, 6, and 8 Weeks

Most veterinarians work from a version of the following schedule, adjusting as needed based on your litter's specific situation:

 

Week 2: First Treatment

By two weeks of age, puppies are old enough for their first round of deworming, and early enough that treatment can get ahead of a growing worm burden before it starts affecting weight gain. At this stage, puppies are entirely dependent on the dam and have no independent immune experience with parasites at all — which is part of why starting early matters so much.

 

What to watch for at this stage: Most two-week-old puppies show no visible symptoms yet, even if carrying a meaningful parasite burden. Don't let a symptom-free litter be a reason to skip or delay this first round.

 

Week 4: Second Treatment

The second round, generally at four weeks, catches any newly matured larvae from the initial infection and reduces the ongoing burden before it can significantly impact growth. This is also a reasonable point to start paying closer attention to individual puppies' weight gain relative to their littermates, since early divergence can be one of the first subtle signs of a heavier-than-average burden in a specific puppy.

 

What to watch for at this stage: A visibly rounder, tighter, or more distended abdomen than what's typical after a good nursing session; any puppy who seems to be falling behind the litter in weight.

 

Week 6: Third Treatment

By six weeks, puppies are typically transitioning toward solid food, which is a meaningful point in their development — increased food intake and activity can also mean increased exposure to any parasite eggs present in the immediate environment, even a clean one. The third round of treatment addresses this transition period.

This is often a good point to schedule a fecal test alongside the treatment, particularly if any puppy has shown symptoms earlier in the schedule, since testing at this stage gives you a read on whether the first two rounds have been effective.

 

What to watch for at this stage: Diarrhea or loose stool as puppies transition to solid food (though this can also simply be a normal part of the dietary transition, so context matters); continued weight gain tracking across the litter.

 

Week 8: Fourth Treatment

The fourth round, generally around eight weeks, lines up closely with the typical vaccination schedule and, often, the point at which puppies are getting closer to their go-home date. This round is meant to substantially clear any remaining burden before puppies leave for their new homes.

 

What to watch for at this stage: This is a good checkpoint to do a final visual assessment of the whole litter side by side — coat condition, body condition, energy level — since subtle differences that were easy to miss puppy-by-puppy often become more obvious when you can compare littermates directly.

 

Beyond 8 Weeks

What Continues at the New Home

Puppies typically don't "graduate" from deworming entirely by the time they go home — most vets recommend the schedule continue at roughly monthly intervals through around six months of age, transitioning eventually into a regular adult parasite prevention routine (often the same product used for monthly heartworm prevention, many of which have some activity against certain intestinal parasites as well).

 

This is exactly why the records you send home with each puppy matter as much as the treatments themselves. At minimum, new owners should receive:

1. Dates and products used for every round of deworming completed during your ownership
2. Any fecal testing results, including dates
3. A clear note on what comes next — i.e., "next deworming due around week 10–12, please continue with your veterinarian"

This isn't just a courtesy. It's the connective tissue between your program and the puppy's long-term health, and it's increasingly something buyers expect as part of a complete health record.

 

Fecal Testing

Where It Fits Into the Schedule

Deworming and fecal testing serve different purposes, and it's worth understanding how they work together rather than treating one as a replacement for the other.

 

Scheduled deworming treats presumed infection based on how common and predictable transplacental and transmammary transmission are — you're not waiting for confirmation because the underlying biology makes infection likely enough that waiting isn't worth the risk to a young puppy's growth and health.

 

Fecal testing, by contrast, tells you what's actually present at a given moment — which matters for a few reasons:

1. It can catch parasites that a standard broad-spectrum dewormer doesn't treat, like Giardia or Coccidia, which are protozoa rather than worms and require separate diagnosis.
2. It tells you whether your deworming protocol is actually working, rather than just assuming it is.
3. It flags a puppy who may need a different or extended treatment approach if their burden isn't clearing on the standard timeline.

A reasonable approach many breeders use: fecal test at least once mid-schedule (commonly around week 6) and again before puppies go home, testing either the whole litter or a representative sample depending on your vet's recommendation and your litter's history.

 

Signs That Warrant a Call to Your Vet, Regardless of Schedule

Even with a scheduled deworming protocol in place, certain signs should prompt an unscheduled call to your vet rather than waiting for the next planned round:

1. A persistently pot-bellied or distended abdomen — distinct from normal post-nursing roundness
2. Diarrhea, especially if it contains blood or mucus, or doesn't resolve within a day or two
3. Vomiting, particularly if visible worms are present
4. Poor weight gain relative to littermates, or outright weight loss
5. Pale gums — a possible sign of anemia, especially relevant with hookworm infections, which feed on blood and can cause serious anemia in a small-bodied puppy
6. Lethargy beyond what's typical newborn sleepiness — floppiness, unresponsiveness, or a puppy who seems unusually cool to the touch

Any of these, especially in combination, deserve same-day veterinary attention rather than a wait-and-see approach. Parasite burdens that go unaddressed can escalate quickly in puppies, given how little physiological reserve a neonate has compared to an adult dog.

 

 

 

 

 

 

 

 

A Simple Reference Chart

 

Age	Action	Notes
2 weeks	First deworming	Treat regardless of visible symptoms
4 weeks	Second deworming	Start tracking individual weight gain across the litter
6 weeks	Third deworming	Good point to add a fecal test
8 weeks	Fourth deworming	Final pre-departure checkpoint; consider a second fecal test
10–12 weeks+	Continued deworming at new home	Send full written records home with each puppy

 

 

The Takeaway

A fixed deworming schedule isn't overkill — it's a direct, practical response to how efficiently roundworms in particular move from a dam to her puppies before birth and during early nursing, often with zero visible warning signs along the way. Sticking to the 2-4-6-8 week framework, pairing it with fecal testing at key checkpoints, and sending thorough records home with every puppy gives your litter the best possible start and gives new owners a clear, documented picture of exactly what's already been done and what still needs to happen.

 

For the full picture of how parasite prevention connects across the entire breeding cycle — including what happens well before this schedule even begins — see our complete pillar guide on parasite prevention for Corgi breeders.

 

This article is intended for general education and to support conversations with your veterinarian. It is not a substitute for individualized veterinary care — deworming products, timing, and dosing should always be confirmed with a vet familiar with your litter's specific health history.