Worms: They will quite literally suck the life out of your horse if you let them!

With the lengthening of the days and brief glimpses of sunshine, it is safe to say spring has sprung! Now is the ideal time to consider whether your worming regime is working hard enough to reduce worrisome worm burdens.

Although a seemingly routine task, having an effective worming strategy is crucial in maintaining horse health. Our spring worming tips are sure to provide you with plenty good ideas and food for thought. In addition, we will explore the importance of understanding antiparasitic resistance and how this should play a significant role in the decisions we make about current worming methods and the implications for our horses in the future.

Internal parasites come in all shapes and sizes and before we share our spring worming tips, we thought it best that you know what you are up against and the impact they can have on your horse. Whether we like it or not, we must accept that ALL horses have worms because our horse’s bodies are the perfect host and provide worms with all the nutrition and protection they need to thrive. With adult worms laying up to 10 million eggs per day, it is no wonder we have our work cut out keeping numbers down!

spring worming tips - poo picking

The five most common types of worms found in horses are: small strongyles, large strongyles, roundworms, tapeworms and bots. The lifecycle of each type of worm differs greatly as does the impact they have on your horse’s body. Our spring worming tips will help you to sort out the worms and spot the symptoms. Worms are not only a problem for your horse’s tummy; at some stage in their life cycle, worms migrate through the blood vessels, liver, lungs and gut lining of your horse’s body. Worms, such as, bots, pinworms, round worms and strongyles larvae can cause skin irritations and hives. If left untreated, large strongyles can cause colic and tapeworm can caused the intestines to become irritated and inflamed. Horses under 5 years old are often at greater risk as their bodies and immune systems are not yet fully developed.

As horse’s owners it is important that we have a clear picture of where we are at before commencing treatment. One of our top spring worming tips is to consider having a faecal worm egg count done; faecal egg counts provide a good way of judging how effective our worming regimes are. Westgate Labs offer an excellent range of services to help you weigh up the effectiveness of your current regime and enable you to create a worming program specifically tailored to your horse’s needs. You would simply send of a small sample of dung for testing in the laboratory to determine which type of worm eggs are present in your horse’s body. This means worming can be more carefully controlled rather than indiscriminately worming and hoping for the best.

The active ingredients in horse wormers are quite distinct from each other and work in different ways: The benzimidazole group acts on the adult worms which feeds on the blood and tissue of the horse’s gut. The drug is taken into the blood stream, the feeding worm ingests it and eventually dies; Ivermectin is also absorbed into the horse’s blood stream and acts upon the worm’s nervous system, causing paralysis but Pyrantel embonate is not taken into the horse’s bloodstream, instead it stays in the horse’s gut and paralyses the worms.

Our top 10 spring worming tips:

In addition to faecal egg counts and increased poo picking, here are a few more spring worming tips to help alleviate the burden further and ensure your horse remains healthy all year round:

1. Where possible operate rotational grazing and avoid over-crowding- Although weather conditions in Britain are rarely warm enough to kill worms and eggs on the ground, we can disrupt the cycle by avoiding exposure to the same soiled ground and being mindful not to graze too many horses on the same pasture.

2. Pay attention to the changing nutritional needs of your horses – Your horse’s body will be able to deal with worms more readily if their gut health and immune system are in optimal condition.

3. Avoid introducing new horses without adequate quarantine measures – It is important to take a moment to consider the worm burden of any new horses and be sure not to put new arrivals out to pasture until you have addressed any parasitic issue they may have arrived with.

4. Be savvy when out and about – As tempting as it is to let your horse nibble grass as a treat when out and about, be mindful of the number of visiting horses to some venues. Worm eggs are microscopic and can easily be picked up by horses in high grazing high traffic areas. Even allowing horses to graze grass verges could expose them to greater risk of ingesting worm eggs. Take your own haynets and water buckets with you when you are away from home to limit cross-contamination.

5. Rotate wormers as appropriate- Avoiding over exposure to the same active ingredients will make worming more effective, always consult your veterinarian for further advice if you are unsure how best to treat your horse.

6. Avoid underdosing- ensure you have an accurate idea of what your horse weighs as under dosing is not only ineffective but will only add to the problem in the long run.

7. Have a rigorous worming routine which is adapted to suit the needs of each individual horse – Although it is recommended that horses are wormed every 8-12 weeks, this will be wholly dependent on your horse’s environment and can be adapted based on insights gained from faecal egg counts.

8. Follow the instructions – Administering wormers is not always a job we relish and can sometimes be a bit tricky, but it is essential for us to follow the instructions. Some wormers can be given with food; whereas others work best when the horse’s stomach is empty.

9. Be sure to worm tactically – Although worming regimes dictate that there should be a change to a chemically unrelated wormer even 12 months, no one product is effective against all types of worms and all stages of their life cycles. Using your knowledge of your current situation will mean you can tactically worm to aim for effective control of encysted small redworm, tapeworm and bots at certain times of the year.

10. Take care when harrowing – We already know that the most effective method is a regular removal of droppings from the pasture, but harrowing is often necessary for land management. Unfortunately, harrowing drags the worm eggs and larvae on to the horse’s grazing areas instead of leaving them in the ‘roughs’ which the horses tend to avoid while grazing. Harrowing should be done only in very hot dry conditions so that the larvae will be killed, or the pasture should be rested after harrowing before the horse’s graze. As the British weather is rarely warm enough to kill eggs, it is best to rest a harrowed paddock for a longer period of time.

Worming horses in the spring is essential for keeping them healthy and happy; however, it is crucial to understand antiparasitic resistance and the different types of worms that can affect horses. By following the spring worming tips we have provided, you will be well on your way to keeping your horse free from worrying worm burdens!

Antiparasitic Resistance: We’ve opened up a can of worms.

Antiparasitic resistance is becoming more of a concern within the horse world. There are several causes of antiparasitic resistance, including overuse or improper use of wormers, underdosing, and using the same type of wormer repeatedly. As years pass, worms are showing increasing resistance to wormers containing benzimidazoles as the active ingredient, thus when designing a worming programme, it is important to look at the active ingredient of the wormer, not just the trade name. Simply changing from one brand to another with the same active ingredient will result in an ineffective worming programme that is likely to encourage further resistance. The resistance is genetic and had arisen by spontaneous mutation but once one population of worms has developed a resistance, we begin to fight a losing battle. When wormed with a particular wormer, those worms who are not resistant will be killed BUT those who are resistant will not only live but will produce eggs where all young worms will be resistant too. This will continue until all the worms in the population are resistant to the wormer.

As we become more mobile and take our horses longer distances to shows, pleasure rides etc. we inadvertently add to this problem by helping to carry resistant worms from one place to another. Over time as more of the worm population become unaffected by wormers, the worms will remain in the horse’s body and the parasitic burden will increase having a negative impact on our horse’s ability to thrive.

Inevitably, this will lead to more instances of weight loss and colic. Increasing the dose may be effective in breaking the cycle short term, but the end result is that worms will simply become resistant to the higher dose of wormer. Resistance to wormers containing benzimidazoles has been noted worldwide. Benzimidazoles are showing the widest levels of resistance mostly because this group of wormers were the first safe drugs developed and have been used frequently over the longest period of time. Resistance to the second groups has now been detected.

Invariably, over time, there will be resistance to the only 3 groups of drugs available to treat worms. Aside from these 3 drug groups there are currently no other options available. The continued use of drugs that worms are resistant to will only worsen the situation in the long run.

Luckily the problem is firmly on the radar and there are steps we can all take to slow the resistance. At the recent National Equine Show Claire, from Westgate Labs, has joined forces with other leaders in the equine industry and together they have launched the CANTER initiative which is the first group of its kind worldwide to bring the issue into the limelight. The apt acronym CANTER urges us to consider the catastrophic consequences of ignoring the problem and outlines the susceptibility of your horse to parasite infection by taking the following risk factors into account: Clinical history, Age profile, Number of horses, Test results, and Environment. By considering these factors, you can determine the overall Risk profile of your horse for parasite infection.

It’s important to be realistic about your horse’s risk category.Many of the risk factors which increase the horse’s profile are beyond the limits of our control and are determined by age or pre-existing conditions. Modern
husbandry practices also have a part to play.

An honest and realistic outlook will help you take appropriate measures to safeguard your horse’s health. Although some elements are beyond our control, there are other elements here we certainly have the power to address, such as, more frequent testing and adopting management strategies, like increased frequency of poo picking to break the worm’s lifecycle. By following our spring worming tips and tailoring your worming program to the specific needs of each individual horse, you too can make a difference! Performing faecal egg counts at certain times of the year means we can be sure we have an up-to-date picture and administer wormers only when necessary. By worming according to our horse’s need, we can help stem the flow of resistance.