Thoroughbred horses Clover and Heather at Burford rehoming centre

Horse worming - when to worm your horse

You will probably have read or heard in recent years about the resistance of equine worms to some of the active ingredients in equine wormers.

To make sure the active ingredients remain effective for as long as possible, wormers should only be used as necessary.

Here at Blue Cross we follow a worming flow chart, and worm according to the horse or ponies

Faecal Worm Egg Count (FWEC) results. A FWEC is a faecal sample which is sent to a laboratory to identify the content of worm eggs in the horse’s droppings, this gives a fairly accurate picture of the horses current worm burden.

The results of the FWEC are provided as ‘eggs per gram’ (epg). We do our FWECs in March, June and September. 

To collect a faecal sample:

  • Collect the sample when the horses has been stabled or stood in an individual area so it can be accurately identified as their own dropping
  • Put a fresh faecal sample into a freezer bag for each individual horse 
  • Samples should be less than 12 hours old
  • Ideally collect three nuggets of poo per horse 
  • Label the bag with the horses name and the date and your surname
  • Take samples to the vets as soon as possible or send via a postal service specialising in this service
Worms in horse poo
If your horse has worms, you will notice them in their faeces

Limitations are that FWEC’s do not detect: 

  • Tapeworm burdens - so we tapeworm test in April, this is a postal saliva test provided by Equisal and we worm according to the result
  • Encysted or immature strongyles therefore we worm once a year in mid-November with moxidectin

Benefits of using this program 

  • Targeted treatment of worm burdens (rather than blanket worming)
  • Preserve the effectiveness of current wormers 
  • Reduce costs by reducing wormers used
  • Less chemicals for the horse to process 


— Page last updated 08/10/2019

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