Worming

Worming horses (also known as deworming or parasite control) is an essential part of equine health management.

Parasites such as worms can have a significant impact on a horse's overall health, performance and wellbeing.

Regular worming is crucial to control these parasites, but it should be done thoughtfully to avoid resistance and ensure the horse’s long-term health.

Why Do We Worm Horses?

Horses are commonly affected by a range of internal parasites, particularly worms, which live and reproduce in their intestines. These parasites can cause several issues, including:

Poor coat condition and weight loss.
Colic (abdominal pain).
Anaemia due to blood loss (e.g., with strongyles).
Diarrhoea.
Reduced growth rates in young horses.
Severe infections may lead to intestinal damage, blockages and, in extreme cases, death.

The goal of worming is to reduce the burden of these parasites, prevent health issues and avoid the build-up of resistance to dewormers.

Common Types of Worms in Horses

Small Strongyles (Cyathostomes):
- These are the most common and potentially the most damaging worms in adult horses. They live in the cecum and colon.
- They can encyst in the intestinal lining for long periods, reactivating in the spring when conditions are favorable.
- They cause weight loss, diarrhoea, colic, and can lead to more severe conditions if untreated.
Large Strongyles:
- These worms are larger and cause significant damage to the horse’s blood vessels, particularly in the intestines, leading to colic, blood loss, and sometimes even death.
- Large strongyles are less common today due to effective treatment programs.
Ascarids (Parascaris equorum):
- These roundworms are primarily a concern in young horses (foals, weanlings, and yearlings).
- Heavy infestations can lead to coughing, nasal discharge, colic, and poor growth.
Tapeworms (Anoplocephala perfoliata):
- Tapeworms attach to the wall of the cecum and ileum.
- They are often associated with colic (especially ileal impactions) and can cause other gastrointestinal issues.
- Diagnosis typically requires a blood test or faecal egg count.
Threadworms (Strongyloides westeri):
- Primarily a concern in foals and young horses.
- Transmitted through the mare’s milk or contaminated bedding.
- Can cause diarrhoea, weight loss, and in severe cases, death in foals.
Bots (Gasterophilus spp.):
- The bot fly larvae attach to the stomach lining, causing irritation and ulcers.
- Bots are not as dangerous as some other worms, but they can cause digestive problems and discomfort.

Worming Strategies

1. Faecal Egg Count (FEC) Testing:

A faecal egg count (FEC) is a test that determines the number of worm eggs in a horse’s manure. This helps guide worming decisions by allowing you to target specific worms.
FEC tests can be used to identify high shedders (horses that pass many worm eggs) and low shedders (horses that pass fewer eggs).
You don’t need to worm horses with low egg counts as frequently, while high shedders may need treatment more often.

2. Strategic Worming Program:

Rotation: Rotate between different classes of dewormers (anthelmintics) to reduce the risk of resistance. Different drugs target different species of worms.
Targeted Treatment: Use FEC to determine which worms are present and tailor treatment accordingly.
Periodic Worming: Even if you’re using FEC testing, regular worming should still be done at set intervals, particularly in high-risk seasons (spring and autumn).
Serology testing (Blood sample) is also available for redworm and tapeworm.

3. Deworming Medications:

There are several classes of dewormers, each targeting different parasites:
- Ivermectin
- Fenbendazole
- Praziquantel
- Moxidectin
- Pyrantel pamoate

4. Resistance Management:

Rotating Dewormers: Use different dewormer classes to prevent resistance. Do not overuse one type of dewormer.
Avoid Under-dosing: Always ensure you are using the correct dosage based on the horse's weight.
Pasture Management: Keep grazing areas clean and remove manure regularly. Rotating pastures and using sacrifice areas (places where horses don’t graze) can help reduce parasite load.

Signs That Your Horse May Need Worming:

Weight loss - Despite a good diet and feeding program.
Dull coat - The horse's coat may appear lackluster or rough.
Colic or abdominal discomfort - Worm infestations can cause discomfort, cramping, or more severe colic.
Diarrhoea - Parasitic infections can lead to gastrointestinal issues.
Coughing or nasal discharge - Particularly with lungworms or ascarids.
Behaviour changes - Horses may become lethargic or irritable due to discomfort

If you're unsure about your horse's worming needs or would like advice on specific deworming schedules, please contact us and we can help you develop a tailored plan.