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Risk-Based Worming -  Worm Burden

For healthy horses aged 3-19 years

All horses carry worms in their system.  This is called a 'worm burden'. Horses who have a low worm burden may show no signs of having worms. Heavier worm burdens may show as poor growth rate in young horses, tail rubbing, weight loss, anaemia, through to coughing, diarrhoea, colic and even death. Or they may not show any outward symptoms. 

Best practice worming is for a fecal egg count (FEC) and worm according to result. You can purchase & download FEC testing instructions here.

If a Fecal Egg count is not an option & horse aged 3-19 years, consider the RISK of the horse carrying a heavy worm burden. A horse with a high risk  is wormed more frequently than a horse with a lower risk.  There are various factors that affect the risk. Choose the plan that best suits your horse's environment and activity.

Low Risk

of Heavy Worm Burden

Excellent husbandry and paddock/stable management practices aid in lowering worm burden.

If you practice all of the below then your horse's risk of heavy worm burden may* be low.

  • Paddock size more than half hectare per horse
  • Multi-species rotation (sheep/cattle rotated in same paddock) 
  • Paddocks spelled during hot weather for at least 6-8 weeks
  • Manure removed at least twice a week
  • Horse is fed off ground
  • Horse weight is known and is wormed according to weight

Moderate Risk

of Heavy Worm Burden

Sound worm management practices and husbandry, horses stay mostly on the property has a moderate risk of heavy worm burden.

If you follow the below practices then your horse's risk of heavy worm burden may* be moderate

  • Paddock size more than half hectare per horse
  • Manure removed at least twice a week
  • Horse is fed off ground
  • Horse weight is known and is wormed according to weight

High Risk

of Heavy Worm Burden

Circumstances and husbandry means the horse lives in a high risk environment for a heavy worm burden

If you tick any of these practices then your horses risk of a heavy worm burden may* be high.

  • Horse on agistment or boarding
  • Horses in small paddocks/yards
  • Shared paddocks smaller than 2 hectares per horse
  • Manure not picked up regularly
  • No pasture management for worms (ie spelling, rotation)
  • Horse moves on & off property eg competition
  • Horses weight is NOT known and horse is NOT wormed according to weight

This is general information only and as all horses are different and we recommend you  consult your veterinarian to see if any worming program is suitable for your horse.

* The only way you can determine worm burden is through a fecal egg count.

These programs were put together based on many different sources including:
•    The American Association of Equine Practitioner (AAEP) parasite control guidelines (2013)
•    NSW Department of Primary Industries Primefacts – Worm control in horses (2010)
•    RIRDC Macrocyclic Lactone Resistance on Australian Horse Farms (2015)
•    U-Vet Equine Centre Werribee Deworming Horses June 2017
•    NSW Department of Primary Industries 'Worm Control In Horses - General Principles (2017)