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Puppy Deworming Schedule FAQ — Key Information Every Owner Should Know

Infection/ParasitesQ&AMeongsiljang Veterinary Advisory Board

Puppy deworming should begin at two weeks of age. Regular deworming supports healthy growth and reduces the risk of parasites being transmitted to humans.

Puppy Deworming Begins at Two Weeks of Age

Image of deworming schedule for a 2-week-old puppy

Deworming for puppies typically begins at two weeks of age. Parasites such as roundworms (Toxocara canis) can be transmitted to nearly all puppies through transplacental infection from the mother or via nursing. Therefore, rather than waiting for fecal test results, it is recommended to start preventive (empirical) deworming at two weeks of age. In particular, nursing puppies may not shed parasite eggs in their feces even with severe infections, so a negative test result does not necessarily mean they are safe. Deworming is more effective when performed on both the puppies and the mother.

2 weeks of age: Administer the first preventive deworming dose to reduce transplacental and milk-borne infections.

4 weeks of age: Repeat deworming at two-week intervals, and manage the mother’s health concurrently.

6 weeks of age: Continue management at the same interval, adjusting as needed based on infection risk.

8 weeks of age: Administer an additional deworming dose around two months of age, and continue monitoring with periodic fecal examinations thereafter.

Deworming Timing Depends on Age and Parasite Type

The timing of deworming for puppies depends not only on their age but also on the type of parasite, environmental factors, risk level, and fecal test results. However, since roundworms (Toxocara canis) are transmitted to nearly all puppies through transplacental infection from the mother and via nursing, it is standard practice to begin preventive deworming at two weeks of age, regardless of test results. "Ascaris" and "roundworm" refer to the same group of parasites (Toxocara) and are not distinct types. The choice of medication and treatment schedule should be determined in consultation with a veterinarian.

Roundworms (Toxocara canis): Can be transmitted transplacentally and through milk; begin preventive deworming at two weeks of age.

Hookworms (Ancylostoma): Severe symptoms can occur even in nursing puppies, so early management is necessary.

Repeat deworming: Repeat treatments at two-week intervals after the first dose, with an additional treatment around two months of age.

Parasite life cycle: Plan treatments by considering both the duration of drug efficacy and infection risk; veterinary consultation is essential.

Image of deworming medication for puppies

How to Determine the Deworming Schedule?

Deworming schedules for puppies vary depending on their age and the risk of parasitic infection. Since parasites like roundworms are commonly transmitted in utero or through the mother’s milk, it is standard practice to begin the first deworming at two weeks of age and repeat it every two weeks. Typically, puppies undergo several deworming treatments at two-week intervals during their early weeks, with an additional treatment around two months of age. However, applying a uniform schedule to every dog is challenging. Once a dog reaches adulthood, deworming should be maintained only when necessary, based on regular fecal examinations and risk assessments, in accordance with veterinary guidelines.

2 weeks of age: Begin the first preventive deworming.

4 weeks of age: Repeat deworming at two-week intervals.

6 weeks of age: Continue management with the same interval.

8 weeks of age: After an additional deworming around two months of age, manage based on risk assessment and fecal examination. Regular fecal testing is recommended.

Key Parasites and Recommended Medications by Deworming Stage

Item	Main Parasites	Recommended Medication	Cycle
2 weeks of age	Roundworm (Toxocara canis)	Broad-spectrum dewormers such as fenbendazole	Preventive first deworming against transplacental and lactogenic infection
4 weeks of age	Roundworm, hookworm	fenbendazole, pyrantel, etc.	Repeat deworming at 2-week intervals
6 weeks of age	Roundworm, hookworm, whipworm	fenbendazole, milbemycin, etc.	Repeat deworming at 2-week intervals
After 8 weeks of age	Parasites subject to risk assessment	Medication based on risk assessment	Regular management based on fecal examination

The type and dosage of medication and the deworming schedule are adjusted by the veterinarian to fit each individual situation.

What to Watch for After Administering Deworming Medication?

After giving your dog deworming medication, it’s important to closely monitor their condition. Some dogs may experience side effects such as nausea, diarrhea, or lethargy. While these reactions are usually temporary, you should seek veterinary care immediately if symptoms are severe or persist.

Nausea or vomiting: These may occur after administration, so keep an eye on your dog’s appetite.

Diarrhea: This can happen as a gastrointestinal response.

Lethargy: Temporary fatigue may pass on its own, but persistent lethargy requires attention.

Fever: If fever is accompanied by other changes in condition, consult your veterinarian.

If any adverse reactions occur after administering the medication, contact your veterinarian. This is especially important with certain potent dewormers (e.g., ivermectin-based products), as the risk of side effects can vary depending on breed and genetic sensitivity, making ongoing observation essential.

Image showing how to observe your pet’s reaction after giving deworming medication

Seek Veterinary Care Immediately for Severe Reactions After Deworming

If your dog experiences difficulty breathing, seizures, severe diarrhea, or bloody stools after taking deworming medication, seek veterinary care immediately. These symptoms may indicate an allergic reaction or serious side effects. Dogs with a genetic sensitivity to ivermectin-based medications are at risk of developing neurological symptoms, so prompt veterinary intervention is essential.

Consistency and Record-Keeping Are Key to Managing Deworming Schedules

When managing your dog’s deworming schedule, consistency and record-keeping are the most important factors. By documenting each deworming session, you can significantly reduce the risk of missing a dose. Utilizing smartphone alarms or a calendar is also highly recommended.

Record-keeping methods: Use a calendar, a dedicated app, or a simple notebook.

Alarm settings: Set a reminder for one day before the scheduled deworming date.

Veterinary consultation: Regularly check your dog’s overall health status with your vet.

Environmental management: Immediately remove feces after elimination and disinfect toys.

Food hygiene: When storing dry kibble, ensure it is kept in a dry environment to prevent moisture buildup.

Maintaining these records forms the foundation of long-term health management for your pet.

Image of an app for recording a puppy's deworming schedule

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Is it safe to give deworming medication to a one-week-old puppy?

At one week old, puppies are still too young for deworming, which typically begins at two weeks of age. Because parasites like roundworms are transmitted to nearly all puppies in utero or through their mother’s milk, the standard protocol is to start preventive deworming at two weeks without waiting for fecal test results, and then repeat the treatment every two weeks. Please consult your veterinarian to determine the appropriate medication and dosage.

What happens if you miss a dose of dewormer?

If you miss a deworming dose, the risk of re-infection with parasites increases. Administer the medication as soon as possible and consult your veterinarian for a re-evaluation.

Can I buy deworming medication at a pharmacy?

Deworming medications require a veterinarian’s prescription. While they may be available at pharmacies, the correct dosage and timing should be determined through consultation with your vet.

When should I give my pet deworming medication?

It’s usually best to give this medication on an empty stomach, but the timing can vary depending on the type of medication and your dog’s condition. Please follow your veterinarian’s instructions for the appropriate time and method of administration.

Do I need to give my pet dewormer for its entire life?

Even adult dogs may need regular deworming based on routine fecal exams and risk assessments. Monthly deworming isn’t essential for every dog; the decision should be tailored to each dog’s individual risk level.

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References

[1] Principles and Practices of Canine and Feline Clinical Parasitic Diseases, 2022

[2] Plumb's Veterinary Drug Handbook, 10th Edition, 2023

[3] The Cat, Clinical Medicine and Management, 2nd Edition, 2021