Is it really time for the ‘big’ worming treatment?
The topic of worms is a gross subject for many horse owners, and they would rather worm their horse several times a year than risk a worm growing inside their horse.
It’s referred to as ‘prophylactic deworming’, but the term could hardly be more misleading. Worm treatments are chemical substances that kill worms. So, only if there is a worm burden, can the active ingredient in the paste kill those worms.
If there are no worms present, then the worming treatment only puts a pointless chemical strain on the horse’s metabolism, most of the active ingredients are absorbed through the intestinal mucosa and then have to be detoxified and disposed of by the liver and kidneys.
In this respect, wormers are comparable to antibiotics – no one would think of simply giving their horse a ‘prophylactic’ course of antibiotics twice a year. This is because antibiotics only work against bacteria when a bacterial infection is present.
Similarly, worm treatments only work if a worm infection is present. And just as with antibiotics, we have produced a lot of resistance through the careless administration of worm treatments.
Unnecessary, ‘prophylactic’ medication causes resistance
Around 80% of worm strains are now resistant to some worming products.
If we continue like this, we will soon face the same problem as with antibiotics: that there are worms that are no longer susceptible to anthelmintics (multiresistant). Then you have a real problem if the horse picks up such parasites.
Host-parasite relationship
It is therefore time to rethink and to take a closer look at the subject of parasite-host relationships.
Horses, like all other mammals, have always had to deal with parasites in the course of their evolution. The fact that the horses did not become extinct over the course of millions of years is due to the fact that the parasite has no real interest in killing its host.
Without a host, the parasite dies too. Therefore, in most cases, a balance is established between hosts and parasites – the host develops strategies through feeding behaviour, hygiene, immune response, etc. to prevent excessive colonisation by parasites.
In the wild, horses will graze in a particular area for a while and also defecate there. They no longer eat where they defecate, which can be seen from areas in the pastures if you don’t poo pick. Once the forage has been eaten, the herd moves on.
The intestinal parasites, whose eggs or larvae are excreted with the faeces, remain on the surface with the faeces. As the horses move on, the risk of them becoming re-infected decreases, that is the hygiene aspect.
In addition, wild horses eat a variety of herbs that seem to minimise worm infestation. Experts are still debating how these plants work. It is generally assumed that the plants contain active ingredients that alter the intestinal environment in such a way that it becomes ‘unpleasant’ for parasites.
They do not have a direct killing effect (unlike dewormers), but rather prevent parasites from colonising the intestines so effectively. This could also explain why, over time, less resistance has developed to the active ingredients of these plants than to our worm treatments, which have a killing effect on worms.
And finally, the immune system learns to recognise the different worms during the horse’s youth and to fight them specifically. Therefore, horses under the age of six are much more likely to suffer from worm infections than adult horses.
Hygiene plays a large part in prophylaxis
What does this mean for our domestic horses? We can utilise the same mechanisms that horses have been using for millions of years. In terms of hygiene, this means mucking out daily, whether it’s in the stable, paddock or field. The less contact the horses have with faeces, the lower the risk of infection.
Worm larvae like it dark and moist and cannot cope well with dryness and sunlight. Therefore, you should mow down any rank patches in the pastures by the autumn at the latest and dispose of the potentially worm-infested mown material on the muck heap (do not feed it!). .
Always let light and air reach areas where manure was deposited. Thoroughly muck out the stables every day and allow them to dry thoroughly: remove the bedding to the edges, allow the floor to dry out, then add more bedding. Since you can never remove all the muck from the bedding, you should also change all the bedding regularly.
Long-lasting bedding (formerly known as deep litter) increases the risk of worm infections it is simply impossible to remove all of the excrement completely, and excrement residues that stick to the bedding may contain worm eggs or larvae.
It is also important to ensure that the horses cannot soil their hay, by using racks, hay nets or other devices. Hay mixed with manure should be disposed of. Provide enough forage that the horses are not forced to eat their own dirty bedding or to fish hay stalks out of the mud of the paddock, which is full of faeces.
Supporting the immune system
The immune system can be supported very well with herbs, especially in autumn, when the risk of infection from bacteria, fungi and viruses increases due to changing weather conditions to cold and wet weather. Immuno Herbs from OKAPI, for example, offer suitable support.
Herbal mixtures that support the liver and kidneys also relieve the immune system, as it is not only responsible for dealing with infections, but also for circulating waste products and toxins.
A healthy gut and gut flora are essential for a stable immune system
The largest immune organ is the intestine, where we find around 70% of the immune system in the intestinal mucosa. The better the intestines can work and the healthier the environment, the more effectively the immune system can work. For a healthy gut, it is essential that horses have constant access to hay.
Feeding breaks are just as harmful for a horse’s intestines as large amounts of concentrated feed or plenty of carrots/apples, but also ‘structured muesli’ or haylage.
Horses are simply not evolutionarily designed to eat such feed; it puts a strain on the natural microbiome (gut flora) and thus also on the horse’s immune system.
In the wild, horses look for plants with a high proportion of bitter and tannic substances to stabilise their intestines. Since sweet grasses make up the majority of our hay, these plants are often missing from our horses’ diet.
Feed herbs selectively
It can be supplemented, for example by feeding Sainfoin. It contains ‘condensed tannins’ (tannins), which are also found in green tea. Studies have shown that Sainfoin has a worm-expelling effect in small ruminants, which is why it is used in landscape management projects with sheep and goats as a natural deworming strategy.
Preliminary studies on horses indicate a comparable effect, which is probably due above all to the positive change in the intestinal environment and thus the strengthening of the immune system.
If you take your horse for a walk past herb-rich nature reserves, you may also notice that they now partially leave grass and instead eat certain plants.
Horseradish, for example, belongs to this category. It contains mustard oil glycosides, among other things, which are thought to have a vermifuge effect. Mugwort is also popular as are walnut leaves, which have a stabilising effect on the intestines of horses due to their various tannins and bitter substances.
Not everyone has the opportunity to take their horse to natural meadows to nibble on herbs. Fortunately, there are now a number of herbal mixtures that have a vermifuge or gut-stabilising effect as their main focus. This can then be given as an ‘autumn protocol’ in the grazing seasons mixed in with a handful of OKAPI Sainfoin.
It must be clearly stated that all these herbal measures are well suited for horses with generally healthy intestines and good immune systems that are currently suffering from a worm infection due to additional stress (change of stables, a new horse in the group, travelling, etc.).
When is a chemical worm treatment unavoidable? When is monitoring enough?
The situation is quite different for horses that have an immune weakness due to inappropriate feeding or living conditions, or due to age, illness or other reasons, and can no longer adequately defend themselves against parasites.
In most cases, there is no way around initially using chemical deworming to rid the horses of parasites to such an extent that there is even a chance of stabilising the gut and immune system again in the next step by optimising feeding and implementing restorative measures.
Whether a horse has intestinal parasites or not can be determined by analysing faecal samples. If you look at the data from the many long-term studies that are now available, you will see that 70% of horses never have a worm infestation requiring treatment, even over a period of years.
The aim is not necessarily to get all horses completely worm-free. Many horses have a low-level infection with small strongyles, which they cope with perfectly well and which remain stable for years without any problems.
No treatment is indicated here, only monitoring. With proper hygiene measures (daily mucking out, etc.), this can even be increased to 80%. This means that if I have a yard with 100 horses, then, as a rule, only about 20 horses are affected by worms at all, provided that proper hygiene is maintained. Accordingly, I don’t need to deworm the remaining 80.
Of the 20% of horses that are identified with worm infections based on faecal samples, about 80% have an infestation with strongyles. These are tiny nematodes that live in the horse’s large intestine. So of my 20 horses mentioned above that are infected at all, 16 have a strongyle infection.
The other four horses have an infection with one of the many other worm species. Second only to the strongyles are the roundworms, which mainly affect young horses and which should always be dewormed if found. They affect an average of 3 of my 4 remaining horses.
Tapeworms and pinworms then follow in third place on the list of the most popular intestinal parasites. Tapeworm respond quite well to deworming, but in the case of pinworms, we are now dealing with strong resistance, so that you often have to deworm several times in succession with different active ingredients before you can get rid of them.
The test should be carried out using an anal smear, which is more reliable than a simple faecal sample in the case of pinnworms. Bots cannot be detected in faecal samples. These can be recognised as early as summer, when the horses have the typical yellow eggs stuck in their coat, especially on the pasterns of the forelegs and around the shoulder joints.
If you have found botfly larvae in the summer, then you should definitely deworm as soon as the frost has passed, and insects are no longer flying. If you then kill the botfly larvae that have overwintered in the horse’s stomach, you interrupt their reproductive cycle. With consistent deworming, you ensure that the botfly gradually disappears from the region and migrates to other areas.
There is room for manoeuvre before the chemical worming treatment
As you can see, worm infections are much less common than most horse owners think, and a lot can be done to ensure that a horse does not become infested with parasites that require treatment. This can be achieved by optimising management, feeding and hygiene.
If you support the horse’s gut with bittering and tanning agents during gut-stressing times such as the spring and autumn grazing season, yard moves, new additions to the group, travel, etc., and add a deworming herbal mixture in spring and autumn, you can keep parasites in check, so that chemical dewormers are not absolutely necessary.
The fewer worm treatments that are given ‘prophylactically’ – in other words, for no reason – the better each and every one of us works to counteract the development of resistance and we keep the medication for cases where it really is necessary to use.
Whether or not there is an infestation should always be monitored by means of faecal samples, and of course by observing your horse. Poor feed conversion, a dull coat, tail rubbing, a distended or bloated belly, unexplained colic, worms or worm parts in the faeces – all of these should prompt you to consider a worm infection and take a closer look with a faecal sample.
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