If you’ve had horses a while, you’ll remember when worming was just something you did every few weeks. Dose them and move on.

This method unfortunately doesn’t work anymore and is out-dated practice, like everything else things move on and improve with research and now we know much more. 

Wormer resistance is a real issue and it’s something every horse owner needs to understand.

What is wormer resistance?

In simple terms, it means wormers stop working.

Some worms survive treatment - Those worms then breed - Over time you end up with worms that the product no longer kills.

So you can keep worming but it’s not actually doing the job, and if you are not testing you'll never know...

Getting worming right

It’s not just about whether you worm, but how you do it.

Make sure you:

  • Use the right wormer at the right time of year for the right parasite. 
  • Dose correctly (weigh your horse, don’t guess)
  • Ask a qualified SQP what wormer is correct for the time of year if you are unsure. 

Why has this happened?

It mostly comes down to how worming has been done in the past:

  • Horses wormed too often
  • Same products used again and again
  • Treating without testing
  • Under-dosing (very common)

All of this gives worms the chance to adapt and become resistant.

Why does it matter?

We don’t have unlimited options, we need to preserve these medications and ensure they continue to be effective. 

There are only a few types of wormer available and when they stop working, we don’t have much left to use.

That’s when you start seeing problems like:

  • Unexplained weight loss
  • Colic
  • Poor condition
  • Ongoing health issues
  • In severe cases, death

What should we be doing now?

Worming needs to be more targeted.

Instead of just doing it routinely, we need to check first and treat only when needed.

Key points:

  • Always test before you treat
  • Some horses carry more worms than others, target those in the herd. 
  • Ensure you are on a worm programme that covers all bases. 

If you want help with testing or putting a proper plan in place, just get in touch. We tailor all our plans to the yard and horses as individuals to ensure effectiveness.