One of the many myths of the Equine Industry is that we should have a regular deworming program. This has resulted in parasites that are resistant to all currently available dewormers.
Initially, the response was to alternate dewormers with different active ingredients, but even this has proven ineffective at preventing medicine resistant parasites.
What is the best way to control parasites then?
Pasture management is the first line of defense. If your horses are in smaller paddocks manure needs to be cleared at least twice a week. If possible small pastures should be rotated for 21 day cycles ( this breaks the life cycle of most equine parasites.)
Stocking rates should be kept low.
Regular fecal counts should be done to establish whether any horses have a high fecal egg count of any species of parasite. I know some people work on fecal egg counts per paddock, but there are usually only a few horses that have high parasite loads, while the others have built up an immunity. For this reason, it is ideal to do fecal egg counts for each horse individually.
The laboratory that does our fecal egg count charges R80 per sample. This will end up saving you money as many of your horses will not require deworming, and you won't be using a dewormer that has no effect on the parasite your horse has if they do have parasites.
Targetting specific parasites when they occur, only in horses that have high fecal egg counts will go a long way to preventing further drug-resistant parasites.
I have included one of the studies on drug resistance. It is not very exciting reading, but I felt it important to have solid references on such a controversial topic. I know there even some vets that still recommend deworming every 3 months. I know of people that double or even triple dose horses, thinking they are preventing drug resistance, but the risk to a horse from this practice is extremely high, and I would never condone the practice. Even if someone's aunty has done it successfully and never lost a horse. That same aunty's horses are likely riddled with ulcers and colic every two weeks, but that is seen as normal in the current horse industry.
Again, I know this is a controversial topic, and I am NOT advocating complete neglect. If you have a horse that is run down and you do a fecal egg count and it comes up clear then it is time to consult your vet. There are parasites that don't show up from Faecal egg counts, or you may have done your egg count during a stage of the life cycle where eggs aren't shed and your vet will recommend doing another in a week's time. For healthy animals, however, a twice year egg count in combination with sound pasture management and appropriate stocking rates is a responsible parasite management protocol.
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