Autumn is an important time to assess parasite burdens in your horse after the grazing season and make a targeted plan for winter. This vet-reviewed guide will cover autumn worming for horses, how to test for tapeworm and redworm, when treatment may be needed, and how to worm horses responsibly.
| Key Takeaways
Start with testing. Explore VioVet's horse worm testing range to help you make a targeted worming plan. |
Why Is Autumn Worming Important for Horses? - Changing Guidelines From Blanket Worming to Testing First
Autumn marks the end of the main grazing season, making it a useful time to assess your horse's parasite burden, as horses may have picked up parasites while grazing throughout the spring and summer.
However, worming is no longer about automatically giving every horse a wormer. Due to increasing resistance, the CANTER (Controlling ANTiparasitic resistance in Equines Responsibly) guidelines recommend moving away from blanket worming and towards a test-led and risk-based approach, treating horses when there is a clear reason to do so.
Below is the CANTER parasite risk profile. It helps to determine your horse’s parasite risk and is recommended for use to discuss with your prescriber.
| Risk Factor | Low | Medium | High |
| Clinical History | No history of worm associated (gastrointestinal) disease | Some history of worm associated (gastrointestinal) disease and/or coexisting disease such as PPID | Clear evidence of worm associated (gastrointestinal) disease in multiple cases, and coexisting conditions such as PPID |
| Age Profile | 5-15 years, no youngstock | 5 years-geriatric, no youngstock | 1*-5 years, and/or geriatric horses with coexisting disease |
| Number of Horses | Low stocking density >2 acres per horse | Medium stocking density 1-2 acres per horse | High stocking density <1 acre per horse |
| Test Results | Repeated low results for worm egg count, tapeworm and small redworm antibody testing in individuals and across the herd | Low–moderate results for worm egg count, tapeworm and small redworm antibody testing in individuals and/or across the herd | High results for worm egg count, tapeworm and small redworm antibody testing in individuals and/or across the herd; and/or wormer resistance identified on the property through worm egg count reduction testing |
| Environment | Closed herd, poo-picked more than once a week, quarantine procedures in place | Occasional newcomers, poo-picked less than once a week, quarantine procedures inconsistent | Frequent movements in and out of herd, not poo-picked and picked infrequently, no quarantine procedures |
Risk Profile: Calculate risk according to the number of features that apply within each category. A greater number of Low risk features indicates a lower overall risk, while a greater number of High risk features indicates a higher risk of parasite infection and associated disease.
What Worms Should You Test Your Horse for in Autumn?
For most adult horses, autumn is a good time to assess both redworm and tapeworm. Using both tests gives you a more complete picture of your horse's parasite risk as you head into winter.
Redworm: Worm Egg Count
A worm egg count (WEC) examines a sample of your horse's faeces for worm eggs. It can help identify horses with significant adult redworm burdens and determine whether treatment is appropriate. A WEC does not detect every stage of the redworm lifecycle, so a low result does not necessarily mean that a horse has no redworm present.
The CANTER guidelines recommend considering the horse's overall risk profile when interpreting results:
- Low-risk populations: Treatment may not be necessary until a higher egg count is reached.
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Moderate or high-risk populations: A lower threshold may be more appropriate for horses considered moderate or high risk.
Tapeworm: Saliva Testing
A tapeworm saliva test can be used to assess your horse's tapeworm burden. Results are generally reported as low, moderate or high.
Treatment is generally recommended where the result indicates a moderate or high burden, rather than routinely treating every horse.
What to Worm Horses With in Autumn
If testing indicates that your horse needs treatment, the appropriate wormer will depend on which parasite is present, the test result, your horse's risk profile, and previous worming history.
Treating Tapeworm
Where a tapeworm treatment is required, the following active ingredients may be appropriate:
- Praziquantel
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Pyrantel at an elevated dose
Your vet or SQP can advise on the most suitable option for your horse and whether there are any factors to consider based on previous treatments.
Treating Redworm
If your horse's WEC indicates that redworm treatment is required, your vet or SQP can recommend an appropriate treatment based on the result and your horse's individual circumstances.
For example, VioVet vet Dr Sophie Meers BVetMed MRCVS suggests: “If the WEC is positive but the tapeworm test is negative, I'd suggest an Ivermectin based product. If both the WEC and tapeworm test are positive, I'd recommend an Ivermectin/Praziquantel combination wormer”.
It is important not to choose a wormer simply because it is traditionally associated with a particular time of year. Targeted treatment helps reduce unnecessary exposure to wormers and slows the development of resistance.
What About Encysted Redworm?
One of the challenges of autumn and winter worming is encysted redworm. These immature redworm larvae can become encysted in the horse's gut wall and are not detected by a standard worm egg count.
Historically, routine winter treatment with moxidectin was commonly recommended to target encysted redworm. However, current guidance has moved away from routinely giving moxidectin to low-risk adult horses.
For horses at higher risk, particularly young horses, treatment may still be appropriate. A blood test for encysted redworm can provide additional information and may be preferable where available and appropriate. This is only available through your vet, since it is a blood test.
If you are unsure about your horse's risk, speak to your vet or SQP before choosing to test and treat.
What Should Your Autumn Worming Plan Look Like?
For an adult horse, a sensible autumn approach could include:
- Test for tapeworm - Use a tapeworm saliva test to assess whether the burden is low, moderate or high.
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Carry out a worm egg count - Use a WEC to assess the horse's redworm burden.
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Consider your horse's risk level - Age, previous worming history, grazing management, clinical history, any co-existing disease such as PPID, and other factors can influence parasite risk.
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Treat only when indicated - If results show treatment is required, speak to your vet or SQP about the appropriate active ingredient.
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Review the plan for winter - Consider the risk of encysted redworm and whether further testing or treatment is appropriate.
How Can You Reduce Your Horse's Worm Burden?
Worming is only one part of effective parasite control. Good pasture management can significantly reduce exposure to parasites and help keep your horse in a lower-risk group.
Useful measures include:
- Poo picking regularly to remove worm eggs and larvae from pasture.
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Avoiding overcrowding and excessive stocking densities.
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Managing grazing to reduce pasture contamination.
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Testing new horses before introducing them to an established group.
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Quarantining new arrivals where appropriate.
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Keeping a record of worm egg counts, saliva tests and wormer treatments.
Harrowing alone is not considered a reliable alternative to poo picking in the UK because weather conditions are not consistently harsh enough to destroy all stages of the parasite lifecycle.
Keep Your Horse Protected
Autumn is a useful time to test rather than automatically treat. A worm egg count and tapeworm saliva test can help you understand your horse's parasite burden and decide whether treatment is necessary based on the test results, your horse's risk profile and previous worming history.
Looking for horse worm testing options? Explore VioVet's horse worm control and testing range.
FAQs
Do you need to worm every horse in autumn?
No. Blanket worming is no longer considered an appropriate approach for most adult horses. Horses can tolerate a low level of worms without developing health problems, and completely eliminating parasites from a population is neither realistic nor desirable. The aim is to keep parasite burdens at an acceptable level while reducing contamination of the pasture and protecting the effectiveness of available wormers.
Instead of automatically treating your horse in autumn, consider:
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Carrying out a worm egg count.
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Using a tapeworm saliva test.
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Reviewing your horse's risk profile.
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Discussing the results with your vet or SQP.
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Treating only where there is a clear indication.
How often should you test your horse for worms?
As a general guide, the CANTER-based approach recommends worm egg count testing around 2–4 times a year, depending on the horse and its risk profile, with tapeworm saliva testing around 1–2 times a year.
Your horse's individual testing schedule may differ depending on factors such as age, grazing arrangements, previous results and overall health.
Keeping a record of test results and treatments can also make it easier to identify patterns and make better decisions in future.
Why is responsible worming so important?
Wormer resistance is an increasing concern in horses. Parasites that survive treatment can reproduce and pass resistant traits to future generations, gradually reducing the effectiveness of available treatments.
There are currently no new equine wormer classes on the immediate horizon, making it particularly important to protect the treatments we already have.
This is why the CANTER guidelines promote a shift away from routine treatment and towards testing, risk assessment and targeted worming.
Written by: VioVet
