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Equine Autumn/Winter Worming Factfile – Small Encysted Redworm

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Description

Small redworms are the most common worms found in horses, with the larval stages of this parasite giving the greatest cause for concern.

All horses should receive an effective treatment against encysted small redworms in late autumn or early winter to prevent small redworms larvae encysting.2

Be prepared to clear the challenge of encysted small redworms and “Time it Right” this autumn/winter.

How much do you know about the dangers of encysted small redworm?   CLICK HERE to watch our video and find out why encysted small redworm are a serious health threat to your horse.

WHAT ARE ENCYSTED SMALL REDWORM?

Small redworm larvae can encyst within the horse’s gut wall throughout the year – especially in autumn and winter. Typically, sudden mass emergence of larvae will occur in spring, damaging the gut, which can cause diarrhoea and colic. This condition is known as larval cyathostominosis and has a mortality rate of up to 50%.

Hidden within the gut wall, encysted small redworm larvae can account for up to 90% of the redworm burden in a horse.

Control needs to be focused on all stages of the parasite’s lifecycle, with specific attention paid to the encysted larvae.

TESTING FOR ENCYSTED SMALL REDWORM

Although faecal worm egg counts (FWEC) are an excellent tool to monitor worm burdens during the spring through to autumn, they will not detect encysted small redworm. This is because the encysted larvae do not produce eggs.

Encysted small redworm is the most potentially harmful stage of the redworm parasite. Horses can harbour several million encysted larvae, yet show a negative or low (< 250 epg) FWEC.

WORMING TO CLEAR THE CHALLENGE OF ENCYSTED SMALL REDWORM

It is important you consider the seasonal worming challenges when formulating your worm control plan.

Every horse should be treated for encysted small redworm in late autumn or winter. Make sure you time it right!

SELECT THE RIGHT WORMER

Remember to select the most appropriate wormer for the parasites you are targeting. Currently, only two active ingredients specifically target encysted small redworm − ask your Vet or SQP how to treat encysted small redworm.

HORSE WEIGHT

Use a weigh tape or weigh scales to determine the weight of your horse. Horses should be dosed accurately, according to their weight. This is important because under-dosing can increase the risk of resistance development.

YOU CAN NEVER BE SURE OF A NEW HORSE’S WORM BURDEN

If their history is unknown they should be quarantined, FWEC tested on arrival at the yard and treated for encysted small redworm and tapeworm. They should then be stabled for at least 48 hours to avoid bringing resistant worms onto your premises.

  • All horses should receive a treatment effective against ESRW in late autumn or early winter to prevent small redworm larvae from encysting
  • Treating with a wormer that does not specifically target ESRW during late autumn and winter can actually increase the risk of a horse developing larval cyathostominosis
  • Due to high documented levels of resistance, it has been advised that a five-day course of fenbendazole should not be used for the treatment and control of ESRW unless a faecal egg count reduction test (FECRT) has demonstrated efficacy
  • Single dose moxidectin has demonstrated high efficacy against ESRW and should be your treatment of choice for the prevention and treatment of ESRW
  • A second moxidectin treatment may be warranted in late winter for yearlings if a FWEC identifies high egg shedding
Comparison of the two licensed treatments against ESRW (cyathostomin) larvae
(moxidectin) (moxidectin & praziquantel)Fenbendazole (FBZ)
DoseSingle dose5-day course
Licensed against benzimidazole (BZ) resistant strainsYesNot recommended where BZ resistance is present
Effect of treatment on gut wall (mucosa)Larvae killed in situ reducing inflammation of the gut wallKilling of larvae can be associated with severe tissue damage that may mimic larval cyathostominosis

 

If you would like more information why not call and have a chat with one of our trained advisors (SQP’S) who are on hand to create a tailored worming control programme that suits you and your horse. Speak to one now on 01250 874486