Horse death highlights dangers of encysted small redworms

stock-eyeA warning has been issued following the tragic death in Britain of an abandoned horse arising from irreparable damage from encysted small redworms.

“Encysted small redworms are one of the most harmful parasites to affect horses in the UK,” says Wendy Talbot, a veterinarian with animal health company Zoetis.

“Unfortunately because they don’t show up in a standard faecal worm egg count, some horse owners are unaware that they must treat for them every year, during the late autumn/early winter, regardless of faecal worm egg counts.”

The young mare was found earlier this month, abandoned and collapsed, in a very weak state in a secluded spot in Surrey.

The story was reported widely on equestrian websites and through social media.

Despite the efforts of the RSPCA and a local vet, nothing could be done to save her.

She was suffering from cyathostominosis, a potentially fatal syndrome caused by the mass emergence of small redworm from their dormant, encysted state.

The case was a stark reminder of the risks of not following a responsible worming plan, said Talbot.

Encysted small redworm are the larval stages of the small redworm that hibernate in the lining of the gut. They usually “wake up” in the early spring and their mass emergence can lead to larval cyathostominosis, causing diarrhoea and colic.

There is a mortality rate of up to 50 percent, but the risk can be prevented with a responsible, timely worming regimen.

Last year’s annual National Equine Health Survey in Britain revealed that one in five owners who claimed to have treated for encysted small redworm used a wormer that was not indicated to treat these potentially lethal encysted parasites.

This suggested many horses could be at risk, according to Zoetis.

All horses can develop larval cyathostominosis but those that may be particularly vulnerable are youngsters, old or immune-compromised horses (such as those with Cushing’s disease), those with an unknown or sub-optimal worming history and those that were not dosed correctly in late autumn/early winter.

“Sadly, I have seen too many cases like this poor mare,” Talbot says.

“If you have a horse showing signs possibly related to a worm burden such as loss of condition, sudden weight loss or diarrhoea, it’s important to contact your veterinary surgeon as soon as possible.”

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