In the wild, horses used to roam freely over thousands of acres, with continuous access to clean and fresh pasture. Worms and horses evolved together in this environment, developing a relatively healthy balance to maintain both populations.
As domesticated horses are kept on more restricted grazing, they have limited opportunity to move onto cleaner pasture and this exposes them to worm re-infection at a much greater level, upsetting the horse/worm balance.
Breaking the life cycle of parasites reduces the amount of worm challenge our horses face. Eggs are passed in the droppings, where they develop into larvae and contaminate the pasture ready to be eaten by grazing horses. An essential part of breaking the cycle is reducing the number of these stages on the pasture, keeping the number of larvae that a horse eats (challenge) to a minimum. In turn, managing the pasture can also reduce our reliance on wormers, reducing the drive for wormer resistance.
Pasture Management Top Tips
A typical horse, weighing 450 kg, produces 5 to 12 pats, approximately 24 kg of dung a day or 10 tonnes a year!
What are faecal worm egg counts (FWECs)?
FWECs measure the number of worm eggs in your horse’s dung and gives an indication of how much your horse’s worm burden is contributing to pasture contamination.
This is a blood or saliva test that identifies tapeworm exposure by measuring antibody levels. There is also an antibody test which can be used to identify small redworm (including ESRW)3,4.
Depending on the results of your horse’s FWEC or antibody test you may be advised to treat or re-test at a future date.
Which Test Should I Use?
|Adult small redworm|
|Adult large redworm|
|Encysted small redworm|
Foals and young horses (< 3yrs of age) usually require a different approach. Speak to your vet or SQP for specific advice.
New horses with an unknown worming history should be quarantined and FWEC tested. Test or treat for tapeworm and encysted small redworm on arrival. They should then be stabled for at least 48 hours to avoid bringing resistant worms onto your premises3.
1. Rendle, D. Vet Times, Equine 2017:Vol 3, Issue 1,
2. Nielsen MK. et al. Vet Parasit 2014; 202; 95
3. Matthews (2008) Equine vet. Educ. (2008) 20 (10) 552-560
4. https://www.austindavis.co.uk/small-redwormblood- test