Worm and Parasite Resistance

1 min. readlast update: 04.20.2021

Resistance to worming treatment is an increasing concern amongst horse owners. Resistance occurs because a very small percentage of worms always had a genetic ability to survive chemical treatment; a strategic approach to worming is important to minimise the risk of resistance occurring.

Reasons for resistance:

  • Worming too frequently can increase chances of resistance. 
  • Under-dosing or using the incorrect active ingredient can increase chances of resistance 
  • If an infestation of worms is not exposed or affected by treatment, resistance amongst this population can occur slowly over time. 
  • Overgrazing and overstocking of pastures can increase resistance amongst the parasitic populations.  

The content of this article should not be considered, or used as a substitute for, veterinary medical advice, diagnosis or treatment. 

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