Puppies should be dewormed for the first time at 2 weeks of age. This early start surprises many new breeders, but puppies can already harbor intestinal worms by the time they’re just one week old. The Companion Animal Parasite Council (CAPC) recommends deworming every 2 weeks until 2 months of age, then monthly until 6 months, and quarterly after that.
Why Deworming Starts So Early
Puppies don’t pick up worms from the environment at first. They get them from their mother, often before they’re even born. The most common roundworm in dogs passes through the placenta into developing puppies during pregnancy. Hookworms take a slightly different route, transmitting through the mother’s first milk during nursing. Either way, worms can be present in a puppy’s intestines within the first week of life.
This is why waiting until puppies show symptoms is risky. Hookworms feed on blood inside the small intestine, and the resulting anemia can be fatal in puppies as young as one or two weeks old. Roundworm infections cause poor growth, a dull coat, and a swollen “potbellied” appearance. In severe cases, migrating larvae cause pneumonia. By the time you see worms in the stool or vomit, the infection is already well established.
The Full Deworming Schedule
The standard protocol looks like this:
- 2, 4, 6, and 8 weeks of age: Deworm every 2 weeks. This covers the period when puppies are most vulnerable and still nursing.
- 8 weeks to 6 months: Deworm once a month. Most puppies go to their new homes around 8 weeks, so this part of the schedule typically falls to the new owner.
- After 6 months: Transition to quarterly deworming or a regular broad-spectrum parasite prevention program.
If you’ve adopted or purchased a puppy and the breeder didn’t complete the initial rounds, your vet will typically recommend deworming every 2 weeks for a total of four treatments to catch up, then shifting to monthly doses.
What Medication Is Used
The go-to dewormer for newborn puppies is a liquid medication (pyrantel pamoate) given by mouth. It’s considered safe starting at 2 weeks of age and is dosed at about 1 ml per 10 pounds of body weight. Because newborn puppies weigh so little, accurate dosing matters. Use a kitchen scale or postal scale to weigh each puppy before treatment. Even small errors can mean underdosing (which won’t clear the infection) or overdosing.
Some deworming products have a minimum weight requirement, which means very small puppies may need to wait until closer to 3 weeks. Your vet can help you choose the right product for your litter’s size and breed.
Don’t Forget the Mother
Deworming the puppies without treating the mother is like mopping while the faucet’s still running. The nursing mother continues to shed parasite larvae in her milk, reinfecting the litter between treatments. The general recommendation is to deworm the mother about 10 days before her expected whelping date and then every 2 to 3 weeks while she’s nursing. It’s important to use a product confirmed safe for pregnant and nursing dogs. Deworming should be avoided during early pregnancy and not started before day 40 of gestation.
Signs of a Worm Problem
Many infected puppies show no obvious symptoms at first. When signs do appear, they vary by parasite type:
- Roundworms: A swollen belly, dull coat, poor weight gain, diarrhea with mucus, and sometimes visible spaghetti-like worms in stool or vomit. Coughing can occur when larvae migrate through the lungs.
- Hookworms: Pale gums (a sign of anemia), dark tarry stools, weakness, and poor growth. In very young puppies, hookworm anemia can be fatal before eggs even appear in a fecal test, which takes at least 16 days from the start of infection.
This is a critical point for breeders: a fecal test on a 10-day-old puppy can come back clean even when a dangerous hookworm infection is already underway. That’s exactly why the deworming schedule starts at 2 weeks regardless of test results.
Side Effects to Expect
Most puppies tolerate deworming well. The most common reactions are mild and short-lived: a brief episode of loose stool, slight decrease in appetite, or tiredness lasting a day or so. You may also see worms in the puppy’s stool after treatment, which actually means the medication is working.
Rare but serious reactions include persistent vomiting, bloody diarrhea, extreme lethargy, difficulty breathing, or signs of an allergic reaction like swelling or hives. These require immediate veterinary attention. For the vast majority of puppies, though, deworming is uneventful.
Why This Matters for People Too
Both roundworms and hookworms can infect humans. Roundworm larvae can migrate through human tissue and, in rare cases, affect the eyes or organs. Hookworm larvae can burrow into skin, causing an itchy rash. Children are at highest risk because they’re more likely to come into contact with contaminated soil or puppy feces. Keeping puppies on a proper deworming schedule, cleaning up stool promptly, and washing hands after handling young puppies are the simplest ways to protect your family.