It used to be a clear matter: The worming treatment for horses was carried out four times a year – regardless of whether or not parasites were present. However, as a result of this procedure, the annoying pests have now built up a resistance. What now? That is the question we want to deal with.
That’s How It Used to Be: Strategic Deworming
Before we deal with new approaches, let’s look again at the “tried and tested” methods. Until a few years ago it was common for horses to be wormed every 3 to 4 months.
These cures were tailored to the currently known parasites and selected according to the season. However, the elaborate (and costly) tests were omitted to check whether the horse was suffering from an infestation at all.
This method clearly has a decisive advantage: (in theory) all parasites are simply rendered harmless. This also includes those who may not have been identified during a fecal examination.
However, one disadvantage has become noticeable over time: the parasites become increasingly immune to the active ingredients. If a horse is dewormed several times, actually for no reason, immune bodies form in its body. If there is actually an infestation, it can result in complex treatment.
Strategically Deworming: This Is How It’s Done
As you will find out later, this strategic deworming method cannot be discarded entirely. That is why we want to shed light on when and how often which wormer treatments are used.
The choice of treatment always depends on which parasites are currently “current”. Stables often hold a collection appointment at which all horses are dewormed with the same preparations. In the meantime, these preparations are often exchanged for comparable variants in order to counteract the development of resistance.
In addition, the use of the various active ingredients depends on the time of year. We have therefore put together a brief overview of when which worming treatment is usually carried out.
- March to July: cure against roundworms. Possible active ingredients: ivermectin, pyrantel, moxidectin, benzimidazole.
- September and October: cure against lungworms, roundworms, and stomach rattles. Possible active ingredients: ivermectin, praziquantel.
- November and December: cure against tapeworms, roundworms, and stomach rattles. Possible active ingredients: ivermectin, pranziquantel, moxidectin.
The Modern Approach: Selective Deworming
After the problem of parasite immunity was recognized, an up-to-date solution was needed. This gave rise to the concept of selective deworming. If such a worming cure is carried out, it is always based on a diagnosis, i.e. a previous fecal examination.
In addition, other worm species are now also included. In addition to tapeworms, stomach worms, and lungworms, as well as gastric rattle larvae, small and large strongyles (bloodworms), awl tails, nematodes, dwarf threadworms, and roundworms are also effectively treated.
Which Horse is Dewormed?
Let us now address the crucial question: When is which horse dewormed? Veterinarians use a traffic light system as a basis. From the age of three, all horses are subjected to regular fecal examinations – twice in spring, once in summer, and once in autumn. From the age of five, there are only two examinations a year.
If fewer than 200 strongyle eggs per gram of feces are found and there are no tapeworms, roundworms, and no awl tails, the horse belongs to the green group. It doesn’t have to be dewormed.
If only worms from a maximum of two categories are noticed, the horse is assigned to the yellow group. It is now being dewormed specifically for these parasites. Horses from the red group – i.e. with more parasites -, on the other hand, have to be dewormed regularly. However, even in the latter case, a fecal sample is always taken to check the effectiveness of the cure.
Decisive Factor: the Immune System
The nice thing about selective deworming is that a horse’s own immune system is also taken into account. In most animals, this itself fends off worm infestation, which is why drug treatment is actually not necessary at all. Only about a third of the horses need the support of a worming cure and that too, only very specifically.
The only exception is the tapeworm. This cannot be repelled by the horse itself and must therefore be treated with a wormer. However, this is no different with humans.
More Expensive But More Effective?
As you can probably imagine, the selective method costs more to start with than strategic deworming. The excrement examinations are, after all, time-consuming. However, for most horses, the costs are balanced because they have to receive less medication.
In addition, with strategic deworming, there is always the risk that the parasites will build up resistance. If that happens, further treatment is also much more costly.
Except for Foals
In principle, the procedure is similar for foals: They are also subjected to fecal examinations. However, it is still worthwhile to subject the young to a regular worming treatment to counteract the small strongyles and the widespread roundworms in particular.
Also important: If worms are found in a foal, all animals of the same age group should also be subjected to the appropriate worming treatment. Spreading is very common here and can thus be prevented.
Dosage of Wormer Treatment for Horses
Regardless of when and how, how much is important. When administering a wormer, the horse’s body weight is always decisive. Each manufacturer usually gives a dosage instruction on the preparation. If it is a worming paste, you can assume that it is usually sufficient for a horse weighing 700 kg.
In order to determine which preparation should be used at the moment or which parasites are currently acute, it is best to contact your veterinarian. This will also create an individual deworming plan for your horse. He will also provide you with the right recipe since wormer cures are no longer freely available for sale in Germany.
Preventing Parasites: You Can Do It
In order to prevent the use of a wormer or the infestation of a horse, you can take a few measures yourself. The hygiene of the stable and pasture is crucial for the occurrence of parasites – they can only survive under certain conditions.
If you carefully peck the willow regularly every two to three days, you are already taking a step in the right direction. Regularly changing pastures and mowing can also greatly reduce the likelihood of worm infestation.
In the barn itself, the risk is reduced through daily mucking out. You should also refrain from floor feeding here, as this is where most of the parasites are located.
Conclusion: Deworming Your Horse – Yes or No?
You can probably never do without deworming entirely. However, then the question is always how you want to proceed. If there is an acute suspicion of an infestation, strategic deworming can definitely be an option. Otherwise, it is definitely advisable to take a fecal sample beforehand and take targeted action against the parasites.
It is best to ask your vet, as he will provide you with an individual plan. He also knows if your horse is at risk of worms but not shedding eggs. In this case, a wormer would still be necessary.