Many people do a fecal egg count before deworming their horses. That in itself is a good idea, because in this way you can combat the parasites in the horse’s belly in a more targeted way. But unfortunately you cannot rely solely on this method. Certain types of worm infections are not or hardly visible in the manure, especially in winter.
A fecal egg count looks at the number of worm eggs in your horse’s manure. A few eggs is not a problem, but if many worm eggs are present, a worm treatment is recommended. Deworming based on a fecal egg count can prevent deworming too often. The latter was sometimes a problem in the past, because worms become resistant to wormers that are given too often.
Red bloodworms at rest
In the fall, the red bloodworm larvae go to rest. They then settle in the intestinal mucosa of your horse. In this resting stage no eggs are produced and you cannot see in the manure that a worm infection is present. Only when the larvae wake up and crawl out of the mucous membrane will your horse become ill. This is usually in the winter. You regularly see this worm infection in young horses. It is therefore wise to give a cure against red bloodworms around the first frost date. Even if there are no eggs in the fecal egg count!
Hornets not visible in the manure
Hornet larvae are also nasty parasites. In the fall they can lodge in the wall of the stomach. They sometimes cause great damage. The larvae can cause stomach bleeding or even rupture of the stomach wall! Unfortunately, you also don’t see hornet eggs in your horse’s manure. That is why a suitable worm treatment in the fall is a very good idea.
The tapeworm can also be difficult for your horse. Tapeworm infections sometimes cause colic and inflammation at the entrance to the small intestine. The eggs of the tapeworm are clearly visible, you can even distinguish them with the naked eye in the manure. They look a bit like rice grains. The problem is that the eggs are deposited very irregularly. It may therefore happen that fecal egg count research does not yield any indications of tapeworms, but that they are there… Another reason for good deworming in the autumn.
When should a fecal egg count be done?
Fecal egg count is very useful, but it doesn’t make much sense in the autumn. Most vets therefore advise to give your horse a strong deworming in the autumn, after the first night frost, which (also) works against red bloodworms, gadfly larvae and tapeworms. In the grazing season it is very useful to do regular fecal egg count. Take a sample from an individual horse, or make a mixed sample of the manure from all the horses in your herd. If too many worm eggs are found in the sample, give all horses an appropriate worm treatment. If not, deworming is usually not necessary. Only horses that are more susceptible to worm infections – such as foals, young horses and pregnant mares – should be dewormed more often.