How to control worms in horses

Last Updated on March 1, 2022 by Allison Price

What are the effects of worms on horses? How can I control worms in horses? When should I worm my horse.

How can I stop my horse from getting worms on his skin?

Horses and ponies are likely to come in contact with various parasites over their lives. A low parasite burden is good for horses’ health. However, it can lead to serious health issues if the parasites are not treated.

Most horses won’t be affected by worm infestation if their owners have a good worm control program and manage their pastures well (see our top tips). These five types of parasitic worms can affect horses in the UK.

  • Redworms of small size
  • Redworms large in size
  • Tapeworms
  • Roundworms
  • Bots

What can you do to stop worm damage from happening?

You must keep your horse’s pastures clean and apply a targeted deworming approach to effectively control worms. Before you deworm your horse, make sure to test them. This test will give you an estimate of the number of parasite eggs your horse has shed in its droppings. It can also help you to treat horses that are most affected.

Because some of the most severe parasites have become resistant to the medications we use, it’s crucial that we adopt a targeted approach to controlling worms. This could lead to worm resistance to all available dewormers in the future. It is important to explore other options to control worms in horses.

What does pasture management do for worm control?

Horses are often infected by worms from contaminated pasture. In just five days, a redworm can grow from an egg in a pile of dung to the larval stage. It can travel up to a metre in dry weather, but can travel up a maximum of three metres in wet conditions.

Although a harsh winter or a dry, hot summer can kill worms in pastures, the UK’s weather is not often severe enough to cause damage. This is why it is important to collect their droppings. The worms will spread further in milder weather, so it is even more important that you remove any droppings from such conditions.

When controlling worms, the main goal is to reduce the amount of worms horses eat while grazing. We have a variety of strategies for managing pastures that can be used to achieve this.

Key points to good pasture management
  • DO NOT pick up droppings. This is an efficient way to control parasitic worms.
  • Droppings should always be collected at least twice a week, especially during hot weather.
  • It is important to keep the muck heap away from horses’ grazing areas.
  • Cross-grazing with cattle and sheep is a good idea. They act as biological vacuum cleaners, consuming parasite eggs or larvae from horses as they graze.
  • Do not overstock your pastures. Allow at least 0.4-0.6 hectares (1-1/4 acres) for each horse.
  • Overgrazing and overstocking encourage horses to graze near the ground and to their droppings, which is where parasite eggs and larvae are most concentrated.
  • To counteract the overstocking of your grazing for weight management, you must pick up droppings more often.
  • Do not harrow the pasture to spread droppings. This spreads parasites all over the place.

How do I properly worm my horse?

The key points to remember:

  • To ensure that your horse gets the right dose, it is important to weigh them before you worm them. You can get an estimate from your local Equine Veterinary Hospital, or a weightape.
  • You should increase the weight of a tape that contains a weightape by 10%
  • To stop horses spitting out the wormer, make sure that the whole thing goes down the horse’s throat.
  • Your horse may spit out a significant amount of the product, increasing the chance of resistance.
  • You can get help from an experienced person if you aren’t confident in worming your horse. To help your horse get used to the process, you can practice with an empty, clean syringe.

Is it more common for horses to be bitten by worms than others?

The key points to remember:

  • Young horses are less immune to worms than older horses. As a result, they have a tendency to be more parasitic and add more eggs to the pasture.
  • Horses that have been kept in a stable for a long time are less likely to become infected by parasites as they are unable to reproduce.
  • Even short periods of grazing, such as when a horse is competing in a competition, can lead to infection. Even a short period of grazing (e.g., during a competition) can lead to infection.
  • Redworm larvae small enough to survive in litter straw bedding can grow.
  • Roundworm eggs can live for many years in stables or other non-pasture settings.
  • Regular turnout is a good thing for your horse’s mental and physical health.
  • The proper management of your horse’s environment and the risks of him getting worms can greatly reduce the chance of them getting it.

How do you treat horses for worms?

What are small redworms and how can they affect your horse’s health?

Cyathostomins are the most serious parasite that horses can be exposed to. They can quickly reproduce and can have severe consequences for horses’ health.

What causes small redworms to cause damage?

Small redworms are adults that feed on intestinal tissue. Large numbers can cause damage to the gut wall. Spasmodic colic is a common symptom in horses, especially young horses.

When we speak of worms, the term “encysted” means hibernating. Small redworms that are encysted at the larval stage will burrow into the gut wall to hibernate. They will then go dormant for several months, although some may remain there for years.

Redworms hibernate in the gut wall, but they are not a problem. Redworm can cause damage to the gut wall if they are present in large numbers, especially during late winter and early spring. Most likely to become ill are horses younger than six years of age.

A small infestation of redworms can lead to serious damage to the intestinal walls if it is not treated. This can reduce the horse’s ability to absorb nutrients and could cause weight loss. A small infestation of redworm can cause death in the worst cases. Less than half of horses that have suffered damage to their large intestine walls will survive.

How can small redworms be diagnosed and treated?

Small redworms can have a variety of clinical signs, making it difficult to diagnose. An adult small redworm burden can be detected by a faecal count, but they don’t lay eggs so encysted smallredworm will not be visible. Horses can appear healthy even though they are carrying significant amounts of encysted little redworm.

The blood test for encysted worm can now be done. Talk to your veterinarian to determine if it is appropriate for your horse. Higher risk horses require a proactive approach to treatment. Your vet can advise you on the best strategy for your horse.

Worms In Horses

Your vet, faecal count provider, or another Suitably Qualified person (SQP), also known as a Registered Animal Medicines Advisor, (RAMA), will recommend the best wormer for treating encysted small redworm. This will typically be moxidectin. If the SQP/RAMA is prescribing the product for your horse, expect to be asked questions.

Any encysted redworm that has been treated with a dewormer can be brought out and cause an acute reaction. You should be cautious when treating a horse with a redworm infestation. If you suspect your horse might have encysted redworm, or if the symptoms are severe, consult your veterinarian immediately. Your vet might recommend that you give your horse additional supportive medication to reduce inflammation in the gut and speed up recovery.

To be treated with Moxidectin, your pony or horse must be older than 6 1/2 months. You must also ensure that your horse or pony is in good health. You can contact your veterinarian or another SQP/RAMA if you have any questions.

Horses can be home to small redworms for long periods of time, even if they are not grazing. Small redworm is not an immune problem in horses and is becoming harder to treat with dewormers. These facts make it more critical to manage the risk with a proper worming and pasture management program.

What are large redworms and how can they affect your horse’s health?

Because they are resistant to most common worming treatments, large redworms (also known as strongyles) pose a less serious threat. Although their prevalence and population has declined, they can still cause serious health problems.

How do large redworms cause damage?

Large redworms, which live in large intestines, produce eggs that are then passed onto the pasture by horses. Horses eat the eggs while they graze. The larvae hatch and then burrow into horse’s intestinal walls. They can cause damage to the blood vessels, causing blockages that stop blood supply to the horse’s intestine. Large redworm can cause severe damage to the horse’s digestive system, which can lead to spasmodic colic. The horse may need to have the affected section of the intestine removed surgically in the most severe cases.

How can large redworms be diagnosed and treated?

Large redworms can be identified by colic, anaemia and weight loss. If necessary, treatment with an ivermectin-based parasite wormer may be recommended for large redworms.

Tapeworms: What are they?

Tapeworm can affect horses of all ages, but it is more common in the elderly and very young horses. Tapeworms are found at the junction of the small and the large intestines and release eggs in the droppings. These eggs are consumed by forage mites, which live on the grazing ground and are then taken by horses as they graze.

Tapeworms can block food passage and cause impaction colic. They can also cause spasmodic colic by irritating the intestine. Tapeworms can lead to intestinal ulcers and even rupture. Folal tapeworms can cause abnormal growth and malnutrition.

How can tapeworm be diagnosed and treated?

Tapeworm symptoms include weight loss, colitis and spasmodic colic. Tapeworms can cause death in the most severe cases. Tapeworm eggs are stored in sections so that they cannot be detected by faecal egg counts.

A saliva test can detect the presence of tapeworm by measuring the amount of antibodies that are produced in response to tapeworm parasites. This test can detect the presence of tapeworms in horses’ systems and indicate if treatment is necessary.

Your vet or testing provider will advise you on treatment. Often, this will include a wormer that contains pyrantel or prazoquantel.

What are roundworms and how can they affect your horse’s health?

Roundworms are also called ‘ascarids’ and affect horses younger than four years of age. They are often only a problem in young horses, so they are sometimes called ‘large roundworms’. Roundworms can block small foals’ intestines due to their size. This can cause impaction colic or rupturing of the intestinal lining. This can lead to death and may need emergency surgery.

How can roundworms be diagnosed and treated?

Roundworms can be diagnosed by symptoms such as coughing, nasal discharge and depression. Roundworm infection can be detected by examining the feces. Your veterinarian or testing provider will be able to advise you on the best treatment, which is likely to include a wormer that contains pyrantel.

What are bots and how do they affect your horse?

The bots are also called gasterophilus intestinalis gasterophilus haemorrhoidalis gasterophilus nasalis and gasterophilus haemorrhoidalis. They lay pale yellow eggs around the horse’s neck, legs and shoulders. The eggs will hatch within five days after being placed. Once stimulated by the horse biting or licking them, they will become larvae. The horse will either eat the larvae or they will crawl to their mouths, where they will burrow into their gums.

The larvae will migrate to the stomach after four weeks.

The larvae will stay in the horse’s stomach for eight to ten more months before being released into the soil. The larvae will then live in soil for 3 to 5 weeks, before emerging as adults ready to begin a new cycle.

How can bots be diagnosed and treated?

To prevent eggs from getting on the horse’s skin, you can use a fly spray or a fly sheet. When removing bot eggs, make sure to not touch your eyes and wash your hands afterward.

A bot fly infection can cause sensitivity in the mouth, dental problems, and even loss of appetite. Sinus infections can also occur in horses, which may lead to the discharge of mucus from their noses.

Bot fly infection can cause stomach problems, including ulceration, swelling, and discharge at the attachment point. Large numbers of larvae can block the horse’s stomach, which can lead to impedance colic. The larvae also eat nutrients, which makes it difficult for horses to maintain their weight and can cause changes in their body and coat.

The larvae of bot fly can burrow into horse skin, causing lesions and tears. Infection can also occur.

The treatment will be determined by your vet, SQP/RAMA or SQP. It is likely to include moxidectin or Ivermectin. To prevent larvae from burrowing in the mouth, treatment should be administered in winter after the first frost, or December, depending on when it occurs.

Allison Price
Allison Price

I’m Allison, born and raised in San Diego California, the earliest memory I have with horses was at my grandfather’s farm. I used to sit at the stable as a kid and hang out with my Papa while he was training the horses. When I was invited to watch a horse riding competition, I got so fascinated with riding!