How Long After Worming Horse Are Worms Expelled?

Last Updated on April 2, 2022 by Urska

If you care for or own a horse, you will know that worm control is an essential part of horse maintenance. It is very likely that at some point you will need to give your horse a dewormer. But how long after worming horse are worms expelled for?

Is It Normal To See Worms In Poop After Deworming?
How Long After Worming Horse Are Wo...
How Long After Worming Horse Are Worms Expelled?

Every horse will come into contact with parasites during their lifetime. This includes worms, and it is normal for horses to carry a small number of worms most of the time. However, if these worms multiply and numbers start to rise, they can become a problem.

When your horse has a high level of worms, you will need to administer a dewormer. These normally work by either killing or paralyzing the worms, stopping them from multiplying. When the wormer has been administered there is only one way out for the worms – via the feces!

So if you need to administer a dewormer to your horse, it is completely normal to see worms in poop after deworming. In fact, it is a good idea to monitor the feces for several days after deworming, to see the type and number of worms being passed. Not a pleasant task for any horse owner, but it will help you see how many worms your horse had!

Are Live Worms In Stool After Deworming A Problem?

It is completely normal to see live worms in stools after deworming. Not all wormers work by killing the worms whilst they are in the body.

If you see live worms in the feces after deworming, don’t panic! These worms will not be able to survive and reproduce outside of the horse’s intestinal system. However, it is a good idea to figure out what type of worms they are to help your veterinary surgeon decide which wormer you should use in the future.

Here are the most common types of worms you might see in your horse’s feces:

  • Redworms – small, thin worms, which are either red or white in color
  • Roundworms – large, stringy yellow-white worms, up to 30cm in length (yuck!)
  • Tapeworms – a long worm which is normally excreted in smaller segments
  • Pinworms – small white worms, very similar to beansprouts in appearance

Safeguard Horse Dewormer – 25 Gm

How Long After Worming Horse Are Worms Expelled For?

After you administer a dewormer to your horse, there will be a short period of time – from hours up to a couple of days – before it begins to take effect. Once the wormer begins to work its magic, it will continue for 24 to 48 hours. During this time you may start to see worms expelled in the feces.

But how long after worming are worms expelled for? Well, this varies from horse to horse. If your horse has a low worm burden, you may not see any worms being expelled at all. For horses with a large worm burden, they may expel worms for 3 to 4 days after deworming. This is because the dead or paralyzed worms can take a long time to exit via the digestive system. So don’t panic if you are still seeing worms after a few days, the wormer is still doing its job!

If you continue to see worms in your horse’s feces after this time, you should seek advice from your veterinary clinic. This is because you may need to get a fecal analysis done, and possibly use a different type of wormer. Never give another wormer without consulting a veterinarian first.

How To Check For Worms After Deworming Your Horse

Although it is not uncommon to see worms in horse poop after deworming, this isn’t always an accurate way to check for worms. If the droppings are not collected straight away then other creatures may have eaten the worms, so you may not always see them. It is also virtually impossible to check the sheer volume of manure that horse’s produce!

Is It Normal To See Worms In Poop After Deworming

The most accurate way to check for worms after deworming your horse is by carrying out routine worm testing on your horse. This is a great way to figure out if a horse needs worming or not, and helps us to ensure that we give the right wormer at the right time. This is known as a targeted worming strategy.

There are various different tests which can be used to check for worms in horses. The simplest one is to take a dropping sample to check for worm eggs. Saliva and blood tests can also be used, particularly for hard-to-spot worms such as tapeworms.

How To Stop Your Horse Getting Worms

With horses, prevention is always better than cure! In the past, wormers would be given all year round, whether the horse had worms or not. This has led to a lot of worms that are resistant to wormers, and we now aim to worm only when absolutely necessary.

So, what are the best ways to stop your horse from getting worms? The number one most effective thing you can do is collect your horse’s droppings. It takes only five days for worm eggs in a dung pile to turn into larvae, which can then be eaten by your horse.

How To Stop Your Horse Getting Worms

Droppings should be collected regularly from pasture, daily if possible. These should be disposed of on a muck heap located well away from the field. Amazingly, worm larvae can travel considerable distances in the right conditions!

It is also important to avoid overgrazing – this is where there are too many horses on a small patch of land. Rotate fields regularly to minimize the worm burden on the land, and remember to test your horses regularly for worms.


So, as we’ve learned, some horses may expel worms for three to four days after worming. How long after worming horse are worms expelled for depends on how high the worm burden of the horse was before worming. It is important to check your horses feces for worms, especially after deworming.

We’d love to hear about your experiences – do you worry when you see worms in your horses poop? Or maybe you have a question about how to reduce your horse’s worm burden? Add a comment below this post and we’ll get back to you!

What are the signs that a horse has worms?

Worms are one of the most common problems in horses. The symptoms of worms can be very subtle and it can be difficult to know when a horse has worms unless you are an experienced horse owner. Most often you will notice that your horse might be loosing weight, his hair coat might become rough and brittle, he might have issues with diarrhea or constipation and might even experience colic or develop respiratory problems. These symptoms are not specific only to worms so it is important to rule out other causes such as inflammation or infection before making the diagnosis of worm infestation. If you suspect your horse may have worms it is important to make sure that you get a fecal sample from him and have your veterinarian examine him to confirm the diagnosis. 

Can worming a horse cause colic?

Yes. The roundworm larvae usually enter the intestine when swallowed with grass. Roundworms then grow and live in the small intestine and when a horse is wormed, they are killed in large numbers. This can form an obstruction within the small intestine and it often results in the horse experiencing impaction colic. A horse that has been wormed regularly is much less likely to have an impaction colic, though. In general, this kind of reaction to wormer is more common in young horses and horses that haven’t been regularly de-wormed.

How do you get rid of worms in pastures?

The most effective way to reduce larval numbers in your paddocks is by removing the manure regularly. By removing the manure, you’ll keep the eggs from hatching into larvae. In warmer climates and higher summer temperature it is recommended to remove manure every three days. If this is not possible, there are other ways to control worms population in pastures. However, if possible, it is best to avoid using chemical pesticides and fungicides that can impact the environment. You can use pasture plants instead. There are a variety of chemical compounds in those plants that have shown some degree of efficacy against parasites, including thujone and tannin. Another good example of a non-chemical method is pasture rotation. Rotating your animals between pastures every month or so helps keep the parasites under control by limiting the amount of time your animals spend grazing on one particular pasture.

Which horse wormers contain moxidectin?

Equest contains the drug moxidectin and is one of the few wormers that can control the important encysted larval stages of small red worms. It has a long period of action against worms, helping to reduce contamination in the pastures for grazing animals. This means that it is less likely to lead to over-dosing and the need for repeated treatments. It is also a long-lasting drug with low toxicity and a wide margin of safety. Moxidectin is used in equine wormer products because it is more stable than other drugs in water solutions, and is particularly effective when used at the correct dose. This makes it an ideal choice for use in horse wormers. It can be used in both feed and water based products, and has been proven effective in both types.