Worming – the basics

WORMING – the basics

From MSD animal health hub with thanks

https://www.msd-animal-health-hub.co.uk/Healthy-Horses/Health/WormingProgrammes Horse Worming Programmes

Tailored horse worming programmes ensure specific worms are targeted with an effective product at the right time.

There are four main classes of anthelmintics (horse wormers):

1.Benzimidazoles: e.g. fenbendazole/mebendazole
2.Tetrahydropyrimidines: e.g. pyrantel embonate
3.Macrocyclic lactones: e.g. Ivermectins/avermectins
4.Praziquantel based wormers (tapeworm treatment ONLY)

Worming throughout the year

It is important that horses are tested or treated for encysted small redworm over the winter period. This is to prevent mass emergence in the spring. There are two types of wormer that can be used for this, fenbendazole or moxidectin based wormers.

Horses only need treating for tapeworm twice a year as the lifecycle takes six months to complete. This should be done in spring and autumn using a praziquantel or a pyrantel based wormer.

During the grazing season faecal worm egg counts should be performed regularly to determine whether horses need worming and if so with which wormer. Your vet/prescriber will be able to advise you on this.

It is, however, important to remember that faecal egg counts cannot detect encysted small redworms or tapeworm eggs, so it is important to treat for these parasites at certain time points during the year as previously described.

The chart is clearer on the msd bub link above.

Parasites – Bots (Gastrophilus)

Bot flies are an irritant to horses during the grazing season. They lay sticky yellow eggs on the horse’s coat which are ingested as the horse grooms itself or another horse.

On entering the mouth the eggs hatch out into larvae, which migrate to the stomach. Here they attach themselves to the stomach lining and continue to develop. Once developed, they will detach and be passed out in the horse’s faeces where they will pupate into flies.