If you've ever adopted a puppy or kitten, you've probably noticed how quickly the deworming questions start — often before the first vaccine is even due. That's because young animals are especially likely to be born with, or pick up, intestinal worms, and left unaddressed, these parasites can genuinely affect a young pet's growth and health. Understanding why the schedule looks the way it does makes it much easier to stay on top of.
Why Puppies and Kittens Are Treated So Early
Roundworms in particular can pass from a mother to her babies before birth or through nursing, which means many puppies and kittens are already carrying worms in their first weeks of life — often without any obvious symptoms. Hookworms can be transmitted the same way and are more likely to cause anemia in young animals because of how they feed. This is why vets typically recommend starting deworming treatments at just a few weeks of age and repeating them every couple of weeks through the first few months, rather than waiting to see symptoms first.
A typical shape (confirm timing with your vet)
- Multiple treatments starting around 2–3 weeks of age, repeated every 2–3 weeks until about 12 weeks old
- Then monthly treatments (often folded into monthly parasite prevention) through about 6 months of age
- Transition to the adult schedule your vet recommends from there, based on lifestyle and regional risk
What Adult Pets Need
Once a pet is past the puppy or kitten stage, the risk doesn't disappear — it just changes shape. Adult dogs and cats can pick up roundworms, hookworms, whipworms, or tapeworms from contaminated soil, hunting or scavenging, fleas (which can carry tapeworm eggs), or contact with other animals' waste. Many monthly heartworm and flea/tick preventives also cover some intestinal parasites, which is one reason vets like to know exactly which product you're using — coverage varies quite a bit between them.
Because most adult worm infections don't cause dramatic symptoms, routine screening matters more than watching for signs. An annual fecal test checks for parasite eggs even when a pet looks completely healthy, and is generally how ongoing deworming decisions get made for adult pets rather than treating on a fixed schedule "just in case."
Signs Worth a Vet Visit
Worms don't always cause visible symptoms, especially in adults, but it's worth calling your vet if you notice a pot-bellied appearance in a young animal, visible worms or rice-like segments in stool or near the tail, weight loss despite a normal appetite, a dull coat, diarrhea, or vomiting. Pale gums in a puppy or kitten can point to worm-related anemia and deserves prompt attention rather than a wait-and-see approach.
Why Households With Kids Deserve Extra Attention
Several common intestinal worms in pets are zoonotic, meaning they can potentially pass to people under the right circumstances — most often through accidental ingestion of contaminated soil or, in the case of tapeworms, through swallowing an infected flea. Young children are at somewhat higher risk simply because of behaviors like playing in dirt or putting hands near their mouths without washing first. This isn't a reason for alarm, but it is a good reason to stay current on your pet's deworming and screening schedule, clean up yard waste promptly, and encourage handwashing after outdoor play — simple habits that meaningfully lower the already-small risk.
It's also worth remembering that a puppy or kitten who seems perfectly playful and energetic can still be carrying a meaningful worm burden picked up from their mother. This is precisely why vets don't wait for symptoms before starting the early deworming schedule — by the time visible signs show up, the parasite load has often already had a real effect on a young, still-developing animal.
Special Situations Worth Flagging to Your Vet
A few circumstances call for more frequent attention than the general schedule: pregnant or nursing mothers, pets recently adopted from a shelter or rescue with an unknown history, pets that hunt or scavenge regularly, and households with young children or immunocompromised family members. In any of these situations, it's worth having a direct conversation with your vet about whether a more frequent testing or treatment schedule makes sense rather than defaulting to the standard adult routine.
The Bottom Line
The early, frequent deworming schedule for puppies and kittens exists because young animals are so commonly infected and are more vulnerable to the effects. For adults, routine fecal testing rather than guesswork is what keeps parasite control on track. Either way, your vet is the right partner for deciding what and when — schedules genuinely do vary by region and lifestyle.