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At vet's, a dog being treated for worms

How Long Does It Take for Worms To Leave a Dog?

Dog dewormers generally are very effective, but when using them, how long does it take for for worms to leave a dog?

Dog ownership almost inevitably comes with having to deal with a worm infection. Dogs are very susceptible to them, but medication will usually fix the problem with little impact on the dog, if any. But after administering the medication, how long does it take for worms to leave a dog?

Worms will start appearing in a dog’s poop about two hours after the medication is first administered, and will continue to appear for up to eight hours on average. It is not unusual to see dead worms for up to two weeks following treatment. If they are alive, however, you should visit the veterinarian. 

We’ll go through deworming your dog and how best to approach it, as well as what warning signs you should be aware of when diagnosing a worm issue. We’ll also look at some other useful health information about deworming and safety.

How Long Will My Puppy Poop Worms After Deworming?

It will take some time after deworming before you stop seeing worms in your puppy’s stool.

In the end, pooping is one of the body’s main ways to eject toxic or unwanted substances, so you can expect the poop of your pup to be the main destination for any dead or dying worms.

Deworming medicine can take effect rapidly but will still cause worms to die over time as it spreads throughout the body and gut. This means that a dog will likely start to pass worms at a minimum of two hours after first taking the medication.

As the medication kills worms over the next 12 hours or so, and then the delay involving the waste process of a body can mean it may take up to two weeks for all worms to be dispelled.

Of course, deworming should only be done under a veterinarian’s supervision and depending on the severity of the infestation, treatment may take several weeks and require frequent or ongoing administration of the medication.

This will lead to the presence of dead worms in your dog’s poop for as long as the worm issue persists. If the worms somehow survive the medication, it is unlikely they will survive out in the open air for long, so deposit the poop and worms in a double bag in an outside bin.

Medication Cycles

Dogs will need to be checked for worms every three months and if there are signs, medication should be started immediately. Some dogs will also require a monthly heartworm preventative.

Ensure that the worm treatment covers all the major worms that your dog is likely to encounter. This means that it will need to prevent not only roundworms, but also tapeworms.

Puppies need to be on a slightly more intensive routine. Generally you should be giving worming treatments every two weeks for the first 90 days.

After that, a puppy can be moved to monthly treatments until they reach adulthood.

The vectors for worms are much more prevalent on rural properties such as farms, and so you can consider shortening the treatment gaps to account for the higher risk of contracting worms.

Signs of a Worm Issue

Dogs often experience issues with worms but these parasites can be easily dealt with without causing any long term damage to your dog.

The clear signs of worms is the presence of them in the dog’s stool or in their vomit. Worms can often cause stomach and digestion issues for a dog, causing them to vomit more frequently than would be expected.

Worms are pretty tough and can survive the journey through a dog’s intestines, so they will often still be alive in the poop.

A worm issue will also tire out a dog and impact on their appetite and energy levels significantly. 

Puppies will go through rapid growth spurts accompanied by huge appetites, so if you notice they’re not eating and not growing at the same rate as similarly-aged puppies, perhaps it’s time for a checkup.

Another common visual sign of worms is diarrhea that contains blood. Worms will wreak havoc with any dog’s digestion and waste processing and the dog’s immune system will try and forcefully eject such foreign objects.

An enlarged belly is also a sign of worms.

If you notice your dog may have worms, it’s best to avoid physical contact with them as the eggs can live in the dog’s fur. Make sure to limit contact from children, the elderly, and anyone with open wounds or is immunocompromised. 

This includes touching and being licked by the dog.

Further, keep in mind that worms can detach from the dog and then take root in your house. This is particularly the case if you have shag carpets or rugs, as worms love to live in such environments.

What Do Worms Look Like?

The most common types of worms are tapeworms, roundworms, and whipworms.


Tapeworms are flatworms, with segmentation and are generally white in color. While infamous for their continuous growth, the actual evidence of them you’ll see is generally only small pieces of their body that have broken off and ended up in the dog’s droppings.


Roundworms are smooth and don’t have segmented body parts. Growing to about 7 inches, they also tend to be a pale white or tan color.


Whipworms are very difficult to spot as they are tiny. Even if you know what you’re looking for, they are paper-thin and see-through.

Although you can find worms living on plants and in soil, one of the most common vectors for worm infestations for dogs is through other dog poop that already has worm eggs in it. Flying insects such as fleas can also be the source of a worm infection.

Final Thoughts

Worms are a common and annoying aspect of dog care, but they are usually very easily treatable with medication. As to how long it takes for worms to leave a dog after taking meds, they start at about 2 hours and can keep leaving for up to 1-2 weeks. Follow your veterinarian’s advice for treatment.

Superb Dog Editor

Superb Dog Editor