Can my dog play with other dogs while being treated for worms?

Yes. Intestinal worms don't pass directly from dog to dog. The risk is environmental, through contaminated stool and soil, so the rule that matters is picking up your dog's poop immediately and completely while treatment is underway.

How often should my dog be checked for worms?

At minimum once a year for a healthy adult dog, as part of the annual exam. Puppies need checking far more often because they're far more likely to be infected. If your dog isn't on year-round broad-spectrum prevention, the Companion Animal Parasite Council recommends fecal exams four times a year.

Can I just buy an over-the-counter dewormer?

You can, but you're guessing at the drug. Over-the-counter products don't cover every worm, dogs are commonly infected with more than one parasite at once, and a wrong-drug treatment looks exactly like a cured dog for about three weeks. Get the fecal test and get the right drug.

Can worms grow in dog poop?

Eggs mature into larvae in the stool, but you can't see that happening with the naked eye, and adult worms never develop out there. They only mature once they've reached a dog's intestines. What that does mean is that a pile of poop left in the yard is a nursery, which is exactly why prompt pickup matters.

Are there home remedies that kill worms?

No. Intestinal worms require prescription anthelmintic drugs, usually more than one dose. Everything you can do at home is about preventing reinfection: cleaning up stool, washing bedding and bowls, and staying on monthly prevention.

Illness & Conditions

You Found Worms in the Poop. What You Can See Is the Least Useful Part.

Identifying the worm by eye is a party trick. The bag in your hand is the actual diagnostic. Here's what to do in the next 24 hours, what visible worms rule in and never rule out, and how to clean up so it doesn't happen twice.

By Dr. Priya Nair, Veterinary Nutrition Writer

August 28, 2026 · 8 min read

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There is a specific moment, and if you’re reading this you may be living it: you tied off the bag, glanced down, and something in there moved.

The instinct is to figure out what it is. Get out the phone, zoom in, scroll through pictures until you find a match. That instinct is understandable and it is mostly a waste of the next twenty minutes, because here is the uncomfortable truth about worms you can see: the visible worm tells you one thing your dog has, and nothing about what else your dog has. The most common intestinal parasite your dog can be carrying, the hookworm, is one you will almost certainly never see in a pile of poop. It’s about a centimeter long, thin as thread, and it stays latched to the intestinal wall until it dies, which can take two years.

So the worm in the bag is not a diagnosis. It is an invitation to go get one.

Here is what to actually do.

The next 24 hours

Keep the sample. Do not flush it, do not toss it in the bin outside. That bag is the highest-value object you own today. Your vet can identify what’s in it in minutes with a microscope, and more importantly, can find the eggs of the worms you can’t see.

Get it in fresh. A stool sample is most useful within about 24 hours. Refrigerate it (yes, in a sealed bag, yes, tell everyone in the house), don’t freeze it, and get it to the clinic.

Don’t reach for the over-the-counter dewormer. This is the single most common mistake, and it is an expensive one. There are drugs on the shelf at every pet store, and some of them will kill some of the worms. If you pick the one that doesn’t cover what your dog actually has, the result is a dog that looks fine for a few weeks while the infection carries on. Multiple simultaneous parasites are common, and the drug that clears a roundworm may do nothing to a tapeworm.

Call the vet even if your dog seems totally fine. Most dogs with worms do seem totally fine. That’s the norm, not a reassurance.

“The phrase I hear most is ‘but he’s acting completely normal,’” says Dr. Ravi Mehta. “That’s not evidence against worms. Plenty of adult dogs carry a real parasite load and behave perfectly, right up until they don’t. The stool sample settles it in an afternoon. Your eyes can’t.”

Okay, but what am I looking at?

You’re going to look anyway. Fine. Here is the field guide, and it is genuinely useful for one reason: it tells your vet where to start.

Roundworms. The one that looks like what a cartoonist would draw: thick, whitish, tapering at both ends, and big. Some species reach 18 centimeters. In severely affected dogs they also show up in vomit.
Tapeworms. You will not see the worm. You will see segments: white to cream, roughly 1 centimeter by 3 millimeters, and they move. Grains of rice with ambition, sitting on the surface of the stool or stuck around the anus. The whole animal can be several feet long, which is a fact you may wish you hadn’t learned.
Whipworms. A thin, filament-like front end and a thick back end, giving a whip shape. White to brownish, 4.5 to 7.5 centimeters. They tend to appear in stool during bouts of diarrhea.
Hookworms. White, small, about 1 to 1.5 centimeters, very thin, and, again, rarely seen at all.

The symptoms nobody connects to worms

Some signs are obvious once you know: weight loss, poor coat, a potbellied appearance (adorable on a puppy, not actually good), decreased appetite, vomiting, diarrhea, mucus on the stool, straining, blood in the stool that’s either bright red or black and tarry, pale gums, weakness, dehydration.

Then there are the two that make no intuitive sense.

Coughing. Why would an intestinal worm make a dog cough? Because some larvae are microscopic and don’t go straight to the gut. They migrate to the lungs to mature, get coughed up, get swallowed, and only then settle in the intestines permanently. The cough is a worm taking the scenic route.

Irritated, itchy feet. Some larvae live in soil for weeks or months and get in by burrowing straight through the skin, most often the paws. The dermatitis you’re treating as an allergy can be the entry wound.

Puppies show all of this more dramatically than adults. They have less margin, and worms are consuming resources a growing body needs. Adult dogs compensate quietly until the worm burden gets large or another illness stacks on top.

How dogs get them in the first place

Nearly every route is something a normal dog does on a normal Tuesday:

Eating another infected dog’s poop
Licking fleas off themselves (that’s the tapeworm route)
Eating the raw muscle of an infected animal, a rabbit or a mouse
Swallowing something off soil contaminated with eggs
Picking it up in utero, across the placenta, before they were even born
Drinking it in with their mother’s milk
Simply walking through contaminated soil

Some of that you can control: don’t let your dog eat wildlife, however badly they want to. Most of it you can’t, and that is exactly why the professional answer is not vigilance but medication, given monthly, before there’s anything to react to.

The part everyone skips: cleaning up

Environmental decontamination is not glamorous, it’s not going to eliminate every egg in your yard, and it is still the difference between treating this once and treating it four times.

Pick up poop immediately, every time, indoors and out. Not “before the weekend.” Immediately.
Wash your hands afterward every single time, bag or no bag. The bag is thinner than you think.
Wash bowls, bedding, and clothing while your dog is being treated.
Clean up puppy accidents fast and thoroughly. Puppies who aren’t potty trained yet are the hardest case, and they are also the least careful about not stepping in, sitting on, and generally rolling around in the problem.
Wash your hands after handling the puppy at all, not just after cleanup.

That last one matters more than it sounds, because humans are what parasitologists politely call an aberrant host for hookworms and roundworms, and it goes badly for us. Toxocara, the dog roundworm, causes an estimated 10,000 human infections a year in the US, mostly in children, and mostly from eggs picked up out of contaminated soil and sandboxes, not from the dog itself. Hookworm larvae in soil burrow into bare human skin and cause cutaneous larva migrans. This is not a reason to panic about your dog. It is the reason the poop scoop is a public health tool.

Treating it, and the thing about the second dose

Once the worm is identified, the right dewormer is prescribed and the actual killing part is usually simple. What surprises people is that most worms need at least two treatments.

That is not a sign the first dose failed. Most dewormers only work on worms that have already arrived in the intestines, and they are unreliable against immature larvae still traveling elsewhere in the body. Your vet times the second dose around how long those stragglers need to finish the trip and grow up. Skip it and you have not cured your dog. You have deloused the front room while the hallway refills.

Heartworm is a different animal entirely, in every sense, and is not treated this way.

Prevention is embarrassingly easy compared to all of this

Monthly heartworm medications also treat most common intestinal worms. For most dogs, prevention is a single chew or pill once a month. The one thing to check: some monthly products do not cover whipworms or tapeworms. Ask your vet which gaps your specific product has and whether your dog’s habits make them matter.

The other lever is the raw one: keep your dog away from raw meat and live prey. That means a leash where wildlife is around, and it means no raw food diet.

When to call the vet

Any visible worm, anywhere, is a call. Any exposure to a dog you know has worms is a call. And at least once a year, worms or not, your dog should have an exam that includes a fecal test, because visual identification is a starting point, and your vet is checking for the parasites you were never going to see.

The worm in the bag did you a favor. It told you to look.