Everything you need to know about winter worming

Small redworm Cyathostomin/Small Strongyles, are one of the most common endoparasites in equines, and during the winter, the larvae (larval Cyathostominosis) hibernate in the gut wall (hypobiotic larvae) and emerge when the weather warms in the spring. At this point they emerge simultaneously and in considerable numbers, causing severe intestinal wall damage. The results of this mass emergence can cause sudden weight loss, abnormal blood conditions, diarrhoea, colic and even sudden death.

Identifying Encysted Redworm in Horses

Encysted small redworm symptoms are not always easy to detect, this stage can’t be picked up by a FWEC (faecal worm egg count). Badly affected horses will often look slightly bloated due to the inflammation. This can make a horse look pregnant or can give the appearance of overweight even. This can clearly be seen in wild horses such as the new forest which have not been treated so therefore have a high worm burden. Although it is thought that typically, native breeds may have a stronger resistance to parasite burdens.

Treatments for Encysted Redworm in Horses

Encysted redworm treatment is therefore essential to the horse’s health and should be combined with a horse worming programme which includes a wormer suitable for encysted redworm in the winter period. Suitable drugs to treat this stage in the UK include a 5-day course of Fenbendazole (Panacur Guard) or a single treatment of Moxidectin (Equest or Equest Pramox), the latter treating for tapeworm at the same time. December or January may be considered as good strategic points for this treatment.

(Image: Small redworm)

Note that the latest guidelines on anthelmintic use suggest Moxidectin should only be used once a year as overuse can increase the risk of wormer resistance long term. It is also important to be aware that the window of opportunity for treating this stage in the horse is after that the constant daytime temperature is of 6 degrees C or less for several days.

Treating encysted redworm in horses should be part of a worming plan for horses in your care with equine horse wormer and part of a horse wormer rotation plan that can be drawn up with the assistance of your vet or SQP (Suitably Qualified Person), trained and qualified to assist you.

(Image: Large redworm) 

It is best to seek advice on redworm in horses as this will help understand the encysted small redworm stage, and when to worm as parasitic worm damage can cause irreversible damage to the gut and other organs of your animals. We have trained staff that would be more than happy to discuss a worming program with you. You can call on 01730815800.

Worming For Winter 2021/2022 

(Updated 30th November)

Late November has already seen numerous 24hr days with temperatures below 6 degrees C. This is important information for horse owners because, in these conditions, small redworms fully encyst into the gut wall in horses that have this parasite. This means NOW is an excellent time to effectively administer wormers! 

These temperatures more commonly occur in late winter, in January/February, so typically horse owners would worm around this time. However, with the current colder temperatures being recorded, many horse owners will want to worm their horses earlier this year.