Prevention is one of the most important pillars of equine worm management. Simply put: prevention is better than cure. There are many different preventive measures that horse owners can take to minimise the risk of worm infection. The aim of preventive measures is to reduce exposure to sources of infection as much as possible and/or to break the worm cycle as much as possible. Below are various preventive measures that can help prevent worm infections as much as possible.

Removing manure from the pasture

It's a time-consuming measure, but also one of the most effective: removing manure from the pasture. The more often, the better. By removing manure from the pasture, you are directly removing a significant portion of the eggs and any larvae present in the manure. This breaks the cycle. All eggs and/or larvae you remove from the pasture in this way can no longer develop into infectious larvae.

However, it is important to realise that even if you remove manure daily, a worm infection can still occur in your pasture. These eggs and/or larvae can survive for quite a long time in your pasture. Removing manure from the pasture can be quite a chore. Of course, there are also all sorts of tools available that you can use to vacuum or sweep the manure from the pasture.

Turning manure piles

The bedding from your horse's stable and the manure you (perhaps) remove from the pasture end up on the manure heap. If you then use this manure to fertilise your pasture, it's good to pay some attention to it. You cannot simply do this without risk.

The warmest part of the manure heap reaches temperatures above 40 degrees Celsius due to the rotting process taking place. Worm eggs and larvae cannot survive in such temperatures. The problem, however, is that the outside of the manure heap is much cooler, and that is precisely an ideal temperature for the eggs and larvae.

If you then spread the contents of the manure heap over the pasture, all these eggs and larvae will end up on the pasture, and your horse will still be exposed to all these parasites. To kill all the eggs and larvae, the manure heap must therefore be turned occasionally, so that the eggs and larvae in the less hot places are also killed. Only then will the worm eggs and larvae in the less warm parts on the outside also be exposed to the heat inside the manure heap and be killed. If you have regularly turned the manure heap, you can spread the contents over the pasture.

Dragging pastures

A widely given piece of advice regarding the control of worm infections is the regular dragging of pastures where horses are kept. Especially if you do not remove manure from the pasture, it is important to drag the pasture regularly. Manure piles, after all, form a good environment for parasites to develop in and then crawl into the grass. Parasites love a moist, warm environment. By regularly dragging the pasture, you break up all manure piles, causing them to dry out and cool down. Therefore, drag the pasture primarily during dry periods (warm or cold). The conditions for worm eggs and/or larvae then become less favourable for survival. Do not drag the pasture during wet periods, as this could have a negative effect.

Topping/Mowing pastures

Another frequently given advice in the field of worm management and the control of worm infections is the regular topping/mowing of the pasture where horses are kept, especially the "toilet areas".

Parasites thrive best in warm/moist conditions. They find these conditions in long grass. That long grass is also the ideal place for them to migrate to, as horses will eat it. In this way, the parasite enters the horse and can develop further.

By topping/mowing the grass, you prevent it from getting too long, thereby making the conditions less attractive for the larvae and reducing the chance of the horse ingesting the larvae again while grazing. This disrupts the worm cycle.

Unfortunately, regularly topping/mowing your pasture does not completely prevent a worm infection, but if you want to set up your worm management properly, regular topping/mowing should certainly be a part of it. And if you really want to give worms as little chance as possible, then preferably do it weekly, preferably in combination with dragging the pasture during dry periods.

Haying pastures

Not everyone has the opportunity to hay (part of) the pasture, but if it is possible, it is certainly recommended. To hay, the grass needs to grow long. Typically, you should count on about 8 weeks if you want to get a decent yield from it. Then it's a matter of waiting for a period of good weather that is long enough to get the hay off the land. Once the grass is mowed, it takes about a week before the bales can be pressed.

During the week that the grass is "loose," it is turned daily. The weather is generally nice and dry, with warm temperatures. These are ideal conditions for the manure piles still on the land to dry out, exposing the worm eggs and larvae to the drought. These conditions are far from optimal for the parasites, and many will not survive.

Regular turning also breaks up the manure piles nicely, causing them to dry out even further and exposing the worm eggs and larvae even more to the elements. Many larvae and/or eggs cannot withstand these conditions and will perish/die. When the bales are pressed, the pasture is essentially swept clean of all manure. These end up in the hay bales where the larvae/eggs cannot develop further and will perish/die.

Rotational grazing

Regularly rotating horses ensures that other preventive measures can be optimally effective. When the pasture is empty, it is important to remove manure and properly top and drag the pasture. Ideally, a round of hay is taken. In this way, you create the most unfavorable conditions for possible life stages of parasites in your pasture. In addition, regular rotational grazing can prevent horses from overgrazing the pasture and having to graze near areas where manure is deposited. These areas of the pasture have the highest risk of contamination.

When rotating pastures, it is also important to ensure that the horses do not carry contamination to the new piece of pasture they are moved to. Prevention is, after all, better than cure. It is important to conduct fecal examination before horses are placed on a new piece of pasture so that measures can be taken if a worm infection is found.

A common misconception is that a pasture is clean after it has rested for a winter. Unfortunately, this is not true. Almost all worm species can easily survive a Dutch winter. Often not as adult worms, but as eggs or in an intermediate host. When temperatures rise again in spring, these eggs will also start to develop again, and the worm's life cycle will simply continue. A pasture is only truly clean if no horses have grazed on it after plowing and reseeding.

Strip Grazing

In addition to regular rotational grazing, strip grazing can also be used to keep the infection pressure on the pasture as low as possible. By implementing strip grazing, you ensure that the horses always have fresh grass available, which prevents them from overgrazing the pasture and grazing close to the areas where manure is deposited. These areas of the pasture pose the greatest risk of worm infections.

Additionally, you can ensure that other preventive measures can be optimally effective. In the strips from which the horses have moved, manure can be thoroughly removed, and the pasture can be properly topped (mowed) and dragged. In this way, you create the most unfavorable conditions for possible life stages of parasites in your pasture.

Other grazers in the pasture

Allowing other animals to graze the pasture can act as a kind of "vacuum cleaner" for existing worm infections. For example, by grazing sheep, goats, or cows, the infection pressure on a pasture can be reduced. However, it should be noted that these animals should not introduce another contamination to the pasture, such as liver fluke. Liver fluke can especially be a problem in wet pastures with ditches around them.

If the pasture is infected with liver fluke, it can help to introduce Indian Runner ducks to eat the liver fluke snails.

Regularly emptying the stable

When it comes to preventive measures in equine worm management, many people quickly think of removing manure from the pasture, prophylactic deworming, dragging or topping the pasture, etc. Yet there is a very important potential source of worm infections that is not often considered: the stable itself!

This was revealed in a study by Mc Girr et al. published in the Equine Veterinary Journal in September 2015. The experimental study specifically focused on the development of bloodworm larvae in straw stables. The study brought several important observations to light:

Under certain circumstances, the stable can be the ideal breeding ground for worm eggs and larvae. Worm larvae love moist and warm environments. If you use bedding such as straw, chopped straw, flax, sawdust, or other natural products, it is quite possible that an ideal breeding ground for worm eggs and larvae will be created.

If the bedding has been in place for longer than a week and manure balls and wet spots are not removed (very) regularly from the stable, you run the risk of a worm infection. If you don't have a deep litter stable, make sure to completely empty the stable every week and remove as many manure balls and wet spots as possible. If you do have a deep litter stable, it is equally important to remove wet spots and manure balls daily. Additionally, with a deep litter stable, it is extra important to ensure that no manure from a horse with a worm infection gets into the stable. And for that, it is, of course, essential to regularly conduct fecal examinations so that you have insight into any worm infections in your horse(s).

Disinfecting stables

Horses can also contract worm infections in the stable. The most common worm infections contracted in the stable are roundworms and threadworms, but bloodworms can also develop further in the stable under the right conditions.

For general stable hygiene and to prevent potential worm infections, it is very sensible to thoroughly clean the stable occasionally. In that case, empty the stable well and spray it clean with a high-pressure washer. After regular cleaning, the stable can be disinfected with an animal housing product (e.g., Halamid). After this, the stable must dry thoroughly before new bedding is added.

Use of herbal mixes, among others

Various herbal mixes are available on the market, aimed at controlling worm infections. Unfortunately, these products are sometimes mistaken for dewormers. Most of these herbal mixes will promote the horse's resistance, making the horse (possibly) less susceptible to worm infections. There are a number of things you should keep in mind when using these herbal remedies:

• Even when using herbal remedies, it is important to monitor your horse closely through regular fecal examination.
  
• The use of a herbal mix does not mean that your horse cannot contract a worm infection.
  
• Herbal mixes support your horse's resistance.
  
• For an existing worm infection, it has not been shown that a herbal remedy is an alternative to regular dewormers.

Source: HippoSupport faecal examination