Worms in your horse: many types and sizes The advice and information platform for all horse and dog enthusiasts.

Worms in your horse: many types and sizes

Horses can carry different types of parasitic worms. Most of these parasites cause problems in the digestive system. But there are also worms that can settle in the stomach. We have listed the most important types of worms for you and also provide a few tips on prevention.**

All types of worms have their own life cycle. This cycle also determines how a horse gets infected with parasites and how to best combat them. Usually it goes like this: Worm eggs can be found in a horse's manure. These eggs develop into small larvae in the manure. When your horse grazes near this manure, these highly infectious larvae can be ingested. The ingested larvae travel through the body to settle in certain areas. Sometimes in the intestinal wall, sometimes in the stomach. The larvae then grow into worms. Adult worms lay eggs, which eventually come out in your horse's manure. And then the cycle starts over again. Worm eggs and larvae can survive for a long time in a moist environment.

Red bloodworm

One of the most well-known parasites in horses is the red bloodworm, also known as small strongyles. These are often found in young horses, but can also infect older horses. For example, when an older horse is in a paddock with younger animals. They are small, thin, red worms that can sometimes be found in the manure. Red bloodworms are mainly found in the large intestine and can cause damage and in severe cases even colic.

Ascarids

Ascarids are also mainly found in young animals, especially foals and yearlings. These are very large, thick white worms. Foals need to be treated regularly with a special worming treatment against ascarids, otherwise they can cause major problems. They start in the intestines, but can also damage the lungs and liver. In the intestines, the large worms can cause a blockage and colic. That's why sometimes, in addition to the special worming treatment against these worms, paraffin oil is also given to infected horses. This helps the manure containing worms to pass easily through the intestines, preventing blockages.

Tapeworm

The tapeworm is not very common, but a bit 'sneaky'. These worms are not typically found in fecal tests. Tapeworms can grow very long. They can attach themselves to the intestines and cause colic. Tapeworms can only be combated with a broad-spectrum worming treatment. Nowadays, there is a saliva test for tapeworms, so you can see if your horse is infected.

Botflies

Botflies lay their eggs in the horse's coat, especially when they are out in the pasture. These eggs (seen as small white-yellow spots) are then ingested by horses when they scratch themselves with their mouths. Or the eggs can be ingested by other horses when they groom each other. The larvae of the botflies then develop in the horse's stomach. This occurs in the fall. Since the botfly larvae attach themselves to the stomach wall, this can cause stomach damage. Many people deworm against botflies in the late fall.

Pinworms

Unlike many other parasites, pinworms are often present in only one or a few individuals in your horse. You can recognize that your horse has pinworms by the tail rubbing. This is because the pinworm lays eggs around the horse's anus, causing itching. It is important to address a pinworm infection properly according to a specific treatment schedule. Otherwise, the pinworms will continue to return.

Stomach worms

Habronema worms are still relatively unknown in the Netherlands, but it seems like they have been more prevalent lately. They have a complex life cycle. The worms live in the horse's stomach and release their eggs in the manure. On that manure, fly eggs are also laid, which develop into maggots. The Habronema larvae that have also emerged in the manure then infect the flies' maggots. After these maggots have matured into adult flies, they can deposit the Habronema larvae on moist areas on the horse's body such as wounds or mucous membranes. Only larvae deposited in or near the mouth are swallowed and can complete their life cycle. You can tell that your horse is infected with these larvae by the small round wounds that appear on the lips. Contact a veterinarian if you see these, as the Habronema worms can be treated with ivermectin or moxidectin.

Worm prevention

Preventing a worm infestation is of course better than treating it. The best way to combat red bloodworm, tapeworm, and ascarids is by maintaining cleanliness in the pasture and paddock and rotating pastures regularly to allow the land to rest. The eggs and larvae will then disappear from the soil. The longer (infected) manure remains, the greater the chances of spreading a worm infestation. To prevent botfly infections, you can remove the eggs from your horse's coat, for example with a pumice stone. And the best way to combat Habronema worms is to prevent contact with flies, for example by using a fly mask. Additionally, it is wise to have fecal tests done multiple times per year.