Result of the worm egg count
If the result shows <50 EPG, it means that no eggs of the specific worm species were detected. Fifty eggs is the detection threshold of the McMaster test as carried out at the parasitology laboratory. Theoretically, it is possible that a donkey has an EPG = 50 for a worm species (10 eggs per gram of feces) while the result shows <50. Very low egg counts are therefore not detected. Such low EPGs have no consequences for health and are not considered an infection. The EPG increases in steps of 50 in the McMaster fecal test.
The following values may appear on the report: <50, 50, 100, 150, 200, 250, 300, 350, 400, etc. The advice to treat a donkey or not depends on the result of the fecal test (= the EPG), the age, and the conditions in which the donkey is kept. If an infection is found, we will always ask you to answer some additional questions so we can provide you with a tailored worm control advice. Whether a donkey has a light or heavy worm burden depends not only on the EPG but also on the age and housing of the donkey.
As a guideline you may use:
Explanation of your result
Congratulations, the fecal test is negative. No treatment is needed.
Every donkey naturally carries worm eggs. It is possible that a donkey has an EPG=10 for strongyles (10 eggs per gram of feces), while the result is still negative. The McMaster threshold is EPG 50 or higher. Very low numbers of eggs are therefore not detected, but they also have no consequences for the donkey’s health. No infection is present.
The fecal test is positive, but treatment is not advised.
For example, the result may show <100 EPG, but the advice is still not to treat. Whether or not your donkey needs treatment depends on the result of the fecal test (= the EPG), the age, and the conditions in which the donkey is kept. Every donkey naturally carries worm eggs, but this does not mean that treatment is always necessary. This depends on the amount of worm eggs found in your donkey’s feces. We provide you with advice based on these findings.
The fecal test is positive. Your donkey needs treatment.
Whether a donkey has a light or heavy infection is determined not only by the EPG but also by the age and housing of the animal. Therefore, we ask you to complete an additional questionnaire so the parasitology laboratory can provide tailored advice.
As a guideline you may use:
This is a question we are often asked. Finding worms afterwards causes a lot of concern and sometimes even leads people to stop doing fecal tests altogether. However, a fecal test is not performed to determine whether or not a horse has worms. Every horse has worms — even one that has just been dewormed. The available dewormers only kill part of the worm population present in a horse.
Please note that eggs are only shed by adult worms. If no eggs are found in the fecal test but there are still developing juvenile larvae, these larvae may become adults within two weeks and then start laying eggs. That is why it is very important to carry out fecal tests frequently.
Finding worms in the manure is nothing to worry about if the horse is fit and healthy. A horse can build up strong natural resistance against gastrointestinal worms and eliminate them naturally. If the population grows and the horse can no longer manage it on its own, then treatment is required. If you find a worm in the manure, take a picture and send it to us by WhatsApp so we can check it for you.
With roundworms, we sometimes even see an adult worm being found on the very day the fecal sample was taken, while the fecal test shows no roundworms present. This can happen when only adult male worms are present, and like other animals, males cannot lay eggs.
We often receive questions about botflies. Because of all the pictures on the internet showing botfly larvae attached to the stomach wall, many owners become concerned. However, botfly larvae are not very pathogenic. Since infection levels are usually low, few donkeys develop problems from botfly larvae. If a donkey owner wishes to treat against botfly larvae, for example when many yellow eggs are visible on the donkey’s coat, we recommend doing this after the first serious night frost. During frost, the free-living botfly adults die, and the risk of reinfection after treatment is absent.
We do recommend always sending in a manure sample in autumn. This provides a clear picture of the infection level on the pastures and allows us to advise on preventing bloodworm problems during the winter.
With this last manure sample, we can create a complete picture of how your donkeys handle worms during the grazing season.
We count all worm eggs and will report the total. First, we count the eggs of adult large and small strongyles. The result does not distinguish between large and small strongyles. We also check the manure for the presence of roundworm and threadworm eggs. You can order additional tests from us for lungworm and liver fluke.
We also check for tapeworm and pinworm, but these are not reliably detected through fecal egg counts. To rule out these intestinal worms, additional testing is recommended.
If tapeworm eggs are found, we will also mention this on the results form. If the fecal test for tapeworm is positive, we can say with certainty that your donkey has tapeworms. However, we cannot rule out that your donkey has no tapeworms if no eggs are found.
If you want to test for tapeworm, it is best to use the EquiSal Tapeworm Test. Tapeworms produce their eggs in packages or segments. Sometimes you can see these segments on fresh manure.
If worms are found, we will always provide you with a personal treatment recommendation. This way, the health of your donkey comes first, and unnecessary deworming is avoided.
Manure is also checked for sand. However, to get an accurate picture of the amount of sand, it is important to test for several days in a row.
You can easily do this yourself. Go to this blog for instructions.
Gasterophilus larvae cannot be detected with a fecal examination. The yellow eggs of the botfly are, however, easy to recognize on the donkey’s coat. This is especially visible in summer and autumn. In late spring, botfly larvae can sometimes be seen in the manure.
Pinworms are almost never visible in the manure. They lay their eggs around the donkey’s anus, so eggs usually do not appear in the feces. To prevent the spread of pinworms within a herd, we recommend deworming in case of a pinworm infection.
Tapeworm eggs are also rarely found in manure. The value of a negative result is limited, as it is still possible that tapeworms are present. Therefore, the laboratory advises testing your donkey twice a year with the EquiSal Tapeworm test.
There are several situations in which a fecal egg count provides essential information about worm infections in your donkey. We have listed some examples for you.
Infectious larvae can survive on the pasture for up to 3 months, especially at lower temperatures. Moderate to severe frost kills the infectious larvae. Research has shown that due to mild winters, pastures can remain contaminated until January. This means that donkeys can indeed become infected well into the winter. A worm control program therefore also includes the winter months.
You can submit pooled samples yourself, but you must mix the dung thoroughly. Take an equal amount of dung from each donkey, place all the dung in a bucket, and mix it well. Then take a small handful of this mixture and send it to the laboratory.
The laboratory does not recommend pooled dung samples. Usually, when testing groups, the result comes back positive, leading to all donkeys being treated. That is not the intention.
For example, if there is a group of 6 donkeys, of which 5 shed no eggs and 1 has an EPG of 1800, a well-mixed pooled sample would result in an average EPG of 300, and the advice would be to treat.
With individual samples, only the donkeys with high egg shedding are treated. In a group of 7 donkeys, this is often only 1 or 2 animals.
When horses and donkeys are kept together, the risk of lungworm infections can increase. Lungworm, caused by the parasite Dictyocaulus arnfieldi, is a worm species that occurs mainly in donkeys. Donkeys often carry this worm without showing any clear signs of illness. For horses, however, it is different: they can become ill from lungworm.
Donkeys can shed larvae for years without appearing sick. This makes them important carriers of the infection. Horses are more sensitive and may develop symptoms even at a lower level of infection pressure. This difference explains why the combination of horses and donkeys requires extra attention.
Our advice is to test the donkey for lungworm. If the result is negative and the horses show no symptoms, it is not necessary to test the horses for lungworm.
It is often said that moxidectin is more effective against bloodworms. However, this only applies to the larval stages of bloodworms. Ivermectin has little to no effect against bloodworm larvae.
Larval stages are only relevant in young horses or in horses sensitive to infections that grazed on heavily contaminated pastures during the previous late summer and autumn. In such cases, the ingested larvae overwinter in a kind of dormant stage in the intestinal wall. For these horses, moxidectin is useful, because treatment (in November/December) will also kill these larvae and reduce the risk of a bloodworm infection.
Due to resistance, we only have two active substances left against bloodworms, and we must use them sparingly.
For treatment during the grazing season, ivermectin is therefore preferred. Moxidectin should be reserved for high infection levels or for winter treatment. With ivermectin, we can achieve the main goal: preventing pastures from becoming heavily contaminated and reducing infection pressure.
We are seeing more and more short courses being offered to learn how to perform fecal tests yourself. Unfortunately, in practice this often goes wrong, with all the risks that come with it. Of course, it is good that horse owners want to learn more about gastrointestinal worms, but due to the complexity of the examination and the interpretation of the results in relation to management practices, expertise is essential.
👉 Take your horse’s health seriously and have fecal tests carried out by professionals.
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