What is Horse Wormer?

Horse wormer is your equines fire wall against intestinal parasites.

Reports say that the second most common cause of colic is an overload of intestinal parasites in your equines gut. Worm populations can increase to the point of blocking the narrow part of the gut.

One of the efficient ways of combating this concern is to use a horse wormer regularly.

How the horse digests food..,

The equine's mouth gathers the food. As they munch and grind, the food begins to break down through a combination of saliva and an enzyme called amylase. This combination is breaking down the food’s starches and also allows for safe passage through the esophagus to the stomach.


The horse’s stomach is considered small for the animal's size. The equine has a “simple” stomach. It is not like sheep or cattle with multi chambers.

The food, now in the horse’s stomach, is broken down further by a combination of hydrochloric acid and other enzymes which are excreted from the stomach wall. The nutrients are digested and slowly start to move down the small intestine. Generally, the stomach does not absorb nutrients and food sitting in the stomach which is naturally mixed with hydrochloric acid and other enzymes can be quite acidic.

Small Intestine

As food moves through the small intestine, it is mixed with enzymes that make the food more alkaline or less acidic. Starch and sugars are broken down to simple sugars.

These starches and sugars are soluble carbohydrates. Sugars pass through the small intestine wall and are absorbed into the blood stream and collected in a blood vessel to be transported to the liver.

Fats are combined with bile salts and enzymes. They form little balls which cross the intestinal walls and collect in the big lymph glands in the neck where they enter the blood stream.

The remainder of the food being digested is broken down for protein and nutrients are sent via the blood stream to the areas where they are needed.

Hind Gut

Now that the food has entered into the hind gut, most soluble portions have been removed. Nutrients have passed through the intestinal walls and been utilized in the areas of the horse’s body that they are required. The Hind Gut is the place for the final digestion which is done through bacterial fermentation.

There are 3 large fermentation sacs. These are the Cecum, the Colons and the Rectum. Bacterial populations are maintained in the horse’s hind gut to break down the indigestible cellulose. This beneficial bacteria passes through the hind gut by the feces.

The horse absorbs and utilizes what the bacteria has digested. It is here that the combination of large sacs joined by small pipes can lead to impactions or blockages like colic.

Did you know.., the small colon and rectum are where the horse’s body absorbs 90% of the water from food stuff which plays a vital role in the water balance of the equine’s system.

Horse Wormer

Horse Wormer is a drug that has been designed to provide minimal harm to the beneficial bacteria.

Horse Wormer is considered to be a neurotoxin and as such affects the nervous system of the worm, however, as bacteria don’t have a “simple” nervous system they are not altered.

Some types of worms that can affect a horse ..,

These are the most common parasite of the stomach. Several species. You may find eggs on the muzzle or legs of your horse.

Are you ready? Adult female bot flies resemble bees. They burrow into the base of the tongue and below the gum line. After about a month in the mouth they double in size and move to the stomach lining where they develop into full grown bots. Bots may also attach themselves to your horses intestines in clumps. In spring bots will pass out in the droppings and re-emerge in the summer months to begin another cycle of eggs.

Larvae are eaten and migrate through the blood stream to the main airways where they stay to develop as adults. Can cause respiratory concerns including coughing.

These are small, white round worms. They live in the large intestine and around the anus. They lay their eggs around the outside of the anus causing irritation. Eggs can be rubbed off in the stable or pasture and thus spread. Watch for excessive rubbing at the tail base.

Tapeworms resemble a tape which is made up of segments containing eggs. Tapeworms pass through the dung which is then eaten by a microscopic mite which remains active in hay or bedding and pasture. Therefore re-infestation can occur throughout the year. Tapeworms can cause colic as well as other internal concerns.

Stomach Hairworm:
These worms live in the stomach and cause irritation and damage to the stomach lining. You may see a loss of appetite and diarrhea.

Small Redworms:
These little devils have the resiliency to become resistant to wormers. They live in the large intestine and excrete in the dung. They can reproduce in huge numbers and pastures can become heavily contaminated with potentially dangerous levels of infective larvae. This small worm burrows into the gut lining to grow. As adults they move back into the gut to lay their eggs. You may see diarrhea, rapid weight loss, colic or to the extreme, death.

Large Redworms:
Burrowing in and out of the artery walls, they alter the supply of blood to the gut of the horse. Results can be colic or to the extreme, death. This is a less common worm.

These eggs are swallowed from the pasture or contaminated stabling. Moving through the bloodstream to the liver and lungs they can, in heavy burdens, block the gut causing digestive problems. You may witness fevers, coughing and loss of appetite. These are the longest of the parasites with a thickness of about a pencil.

The larvae for this worm lives under the skin and around the eye tissue and can be spread by Midges (a 2 winged fly) as it feeds.

Large Mouthed Stomach Worm:
This worm’s larvae is found in the mouth parts of the fly. Horses ingest the larvae and continue the cycle as the eggs live in the stomach to again pass through the manure and be picked up again by the fly. You may find sores which fail to heal.

How does Horse Wormer work?

Horse wormers are designed to be an effective parasite control for your equine companion. Easy, efficient delivery methods, coupled with sound veterinary advice, can be the block between you and your horse and a myriad of health issues from minor irritation to the extreme, being death.

Effective parasite control is related to pasture management and hygiene as well as having an effective horse wormer plan. It is said that one is not effective without the other.

Generally speaking a horse wormer is given orally. Today’s wormers paralyze rather than kill adult worms. Paralyzed parasites will not release their toxins and are unable to resist being discharged from the horse’s gut through manure.

As a side note, the time between a worming treatment should be discussed with your veterinarian for your area. If you are not worming regularly enough, the re-occurrence or eggs in the manure will increase to be re-ingested, thus starting the cycle again and again.

Horse Wormer: What is horse wormer, having a worming plan and figuring out how to apply the wormer paste to your equine companion.

PLEASE NOTE: This web page is based on the research and conversations that we have had with various people and professionals on the subject of horses health and horse wormer requirements and is not intended to replace veterinary care for your animals. We do not accept liability for errors or omissions. A vet, horse nutritionist or other trained professional should always be consulted with any equine concerns, or before changing any feeding or care regime.