An infected pasture can expose horses to parasitic eggs or larvae that become adult worms, eventually released through their manure and shed by them.
Your horse needs to learn how to accept oral medications like wormers or antiparasitics; start by standing next to them and showing them the syringe.
1. Warm up properly
Preparing horses for vigorous exercise requires a proper warm-up session. This enables their heart rate and breathing rate to gradually increase, as well as helping prevent them from becoming overtired or injured during vigorous physical exertion.
Standing close enough to your horse will allow them to keep their head at an appropriate height, which will prevent them from placing their mouth on the bit and pushing out their syringe.
Squirting paste toward the back corner of their mouth might also make them more comfortable, just be wary not to poke their lips or hit their teeth and cause irritation that could make deworming more challenging next time.
Regularly clearing droppings from pastures is also recommended to prevent the build-up of worm eggs, and help your horses consume fewer parasites that pass onto other animals when they graze. Doing this daily during warmer months and once every two weeks during winter will reduce worm infections among your horses as they graze on grasslands.
2. Don’t overdo it
No absolute guidelines exist here; but as a general guideline it is best not to ride your horse on the day they are being wormed if it’s hot as this could cause them to overheat and compromise the effectiveness of any wormer treatments applied that day.
After administering a wormer to a horse, it is highly advised that they remain stabled for 48 hours in order to ensure any remaining worms will fall off into their manure and die naturally – this helps avoid an increase in resistant worms in future treatment regimens.
Notably, it is generally accepted that horses should only be dewormed when their FEC results show levels under the recommended threshold, in order to limit how often and reduce resistance over time. As such, surveillance worming should be encouraged at each change of season – testing your horse for parasites every now and then may also prove helpful.
3. Take it easy
Many horses experience difficulty being dewormed due to how their owners conduct themselves when doing it, rather than any issue on the horse’s part. For instance, approaching them aggressively while tightly gripping their halter and forcing the syringe in their mouth may make them defensive and lead them away from being treated.
Most worms infect horses when they consume eggs from infected pastures and then hatch and develop within their digestive tract and sometimes lung tissue, eventually producing adult worms which shed eggs through their feces, eventually becoming transmissible to other horses in that field.
One reason wormers have become less effective over time is overuse leading to resistant worms taking hold. Certain worms carry genes which allow them to withstand treatment and continue reproducing while susceptible ones die off, so only administer your horse a wormer when necessary. For optimal effectiveness it is wise to give only what your horse requires at any one time.
4. Don’t ride on the day of worming
Now it is widely acknowledged that moving a horse directly back onto clean pasture after being wormed can increase resistance. Resistant worms will survive and breed rapidly, further compounding your problem of wormer resistance on your land.
Your horse should be returned to its former grazing field immediately following treatment in order to reduce resistance by spreading susceptible worms among them. Although this may seem counterintuitive, this action will help minimize resistance on your land and decrease build up of resistance over time.
As long as your horse does not show signs of having a high worm load (e.g. loss of condition, colic, scouring or blood in their dung) then riding them can continue without worry. Just make sure to warm up properly before each ride to prevent overdoing it! For additional advice or assistance regarding product and timing recommendations please reach out to your vet who may offer more tailored guidance and recommendations.
Chris is a passionate learner and writer. When he’s not working on his blog or learning something new, he’s a full-time systems administrator and father of two beautiful girls. Chris loves spending time with his family, reading, writing, and playing hockey.