Ascaris Round Worms – Horse Worms

Do you suspect that your horses may have worms? Here are a few Ascaris Worm Facts: Parascaris equorum, also known as Horse Worms, are a type of Giant Roundworm which resides within affected horses. This article covers how they live and spread and symptoms to look for in horses – plus easy and cost effective treatment of affected animals.

Ascarids are one type of parasitic nematode worms. Also known as giant round worms, they affect the intestinal tract of vertebrates all over the world and can wreak havoc on livestock animals such as horses. Let’s examine the lifecycle, dangers and treatments of ascerids.

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This jar of parasites is on display at my local veterinarian clinic. They came from one of the horses here in rural North America, where parasites can be a real problem. Ascerids usually trouble young horses whose immune system’s are not yet fully developed. They can lead to weakness, depression, stunted growth and potentially fatal colic.

Most ascerids are host specific, meaning that they will grow into adulthood and reproduce in only one single type of host animal. These equine ascerids known as parascaris equorum, occur in horses, donkeys and zebras but are not capable of infecting dogs pigs or humans for instance.

Equine ascaris are usually the size of a pencil, but the females can get much larger – up to 14 inches long. Healthy female ascerids can lay hundreds of thousands of eggs per day. These eggs are passed on into the open and can lay dormant in manure for up to ten years or longer, until they are picked up by other grazing horses. Adult equine ascarids usually reside in the small intestine, however freshly hatched larva will invade the gut wall and travel to the liver via the lymphatic system.


Then after about a week they will molt, reaching the next larval stage, when they migrate to the lungs, traveling through the bloodstream.


From there they are coughed up and swallowed, returning once again to the small intestine, where they can mature into adults, mate and begin laying eggs – typically within just 10 weeks from being ingested. It is common for adult horses to develop an immunity to ascarids; so they are more of a problem with young horses.


If your horse is under 2 years of age, keep an eye out for symptoms such as weight loss, poor growth, lethargy, a rough hair coat, coughing, nasal discharge, pot-bellied appearance and/or colic. This problem can be taken care of with an oral worming treatment by your local veterinarian; also available online if you prefer to take care of it yourself. I will post a link to oral worming treatments if you would like to compare prices on the best horse worming medicines available. Check the link below…


– Here is a link for you to compare the best prices for horse wormer medicine on Amazon: safe-guard horse dewormer on Amazon

This article is also available in a video format on YouTube here:

As far as long term prevention is concerned, it would seem like a good idea to clean up and remove any old manure from the your horse’s living area when possible. We have all seen horses nibble on road apples when they get bored, and that is where the eggs would be picked up. I hope that this has been helpful and informative for my fellow equestrians out there.

Please feel free to leave a comment below, I really appreciate your interest in this segment; the internet and I would like to know what you think about it.

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