When is the right time to worm your horse in winter?
We know we need to worm our horses in winter for Inhibited Encysted Small Redworm (IESR) and Bots.
But it’s really important that we do this AT THE RIGHT TIME in the winter.
So when is the right time to worm your horse?
When you are worming in the winter you will probably be advised to use:
- Equest (to treat inhibited encysted small redworm and bots)
or
- Equest Pramox (if you need to treat for tapeworm too)
(Note you should not use these wormers at any other time of year! See this post on resistance)
The old traditional way was to worm after the first frost – But this is OLD advice!
You should NOT worm using Equest or Equest Pramox straight after the first frost.
Just because there’s been a frost doesn’t mean that redworms suddenly say “Woohoo, let’s encyst into the gut wall and stay there until spring!”.
It’s a proven fact that it doesn’t work like that.
There needs to be a period of frost, and we need to worm for IESR when there’s the least amount of daylight hours.
The lesser daylight hours affects them more than the cold weather.
The optimum time to worm for IESR and Bots is December or January.
At Christmas time is ideal because the shortest day is the 21st of December. And then we’re pretty much guaranteed cold weather in January.
So around Christmas/New Year is actually the absolute best time to do it.
Learn from the past!
There have been warnings in the past about worming for IESR and Bots in November or early December.
If you worm at this time you will very likely have to do it again in spring or at the start of spring.
This is because you’ve done it too early the previous year. The redworms are still encysting and inhibiting.
Equest and Equest Pramox are the ONLY drugs we have to treat IESR.
The more we use them unnecessarily, the less effective they become for the whole equine population.
We need to worm for the INHIBITED encysted small redworm.
The ones that are hibernating in the guts over winter.
They encyst into the gut wall as part of their three-weekly lifecycle anyway.
BUT over winter, with the cold weather and short days, they inhibit in cysts.
They hibernate in these cysts, and that’s why we get the build-up.
So we need to worm when they are in the INHIBITED stage.
Before this stage is too early to be effective.
So is someone has told you to do it ‘after the first frost’ DON’T. They are wrong!
Can’t I just use the new blood test to test for IESR?
I can’t TELL you what to do with your horse.
My passion and my job are to give you the best advice I can, based on my up-to-date expert training and knowledge.
So I make no apologies for telling you that the blood test does have its limitations:
- We cannot test for Bots, so we have to treat for them.
Even if you think your horse hasn’t had bot flies on them, they will have done.
They can very quickly lick the eggs off or the eggs can burrow into the skin before you’ve even seen them.
- Your horse has to have had consistent worm counts of less than 50 eggs per gram throughout the year. (That’s at least four worm counts over the year.)
- The blood test is ONLY A GUIDE.
It shows the LIKELIHOOD of your horse having inhibited encysted small redworm.
It does not give a definite ‘yes they have’ or ‘no they have not’ answer.
It is a guide as to the likelihood of infection and is not guaranteed.
But it’s only deemed to be ‘reasonably accurate‘ IF they have had consistent worm counts throughout the year of less than 50 eggs per gram.
So what does EFECS recommend?
To most of my customers (depending on history), I recommend worming in late December or early January. This is for the following reasons:
A. Because we have to treat for Bots, regardless.
B. There aren’t many horses that consistently come back with less than 50 eggs per gram counts.
C. Because, at the moment, the blood test only shows the LIKELIHOOD of infection. It is not a guaranteed result as to whether they have got inhibited encysted small redworm.
I hope this helps, but if you have any questions please do get in touch. I hate to think of people worrying about their horse’s health and welfare but not knowing where to turn!
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