The Dartmoor Pony Heritage Trust is trying to “put a firewall” in place around the 450-hectare site it leases from Forestry England at Bellever, to protect its 27 ponies.
Other animals on neighbouring commons, at Haytor and Widecombe, are already infected, so the trust is urging riders and walkers to stay out of Bellever, in hopes of stopping the infection spreading to more moorland herds.
Charity chief executive Dru Butterfield said: “The neighbouring [new intake] to the land we lease has contracted strangles, and this strain is particularly nasty.
“We are devastated that our herd, which we go to such extreme measures to care for, are now almost certain to contract this terrible infection.
“We urge the public to avoid any contact with our ponies and to please enjoy them from a distance. If you are a horse owner we would ask you to avoid Bellever until we provide an all-clear notice.”
The trust is working with vets and the Dartmoor Livestock Protection Society.
H&H reported in February that visitors to the moor were being asked to look but not touch, as some of the ponies were carrying strangles.
Anyone who sees a pony with a snotty nose or abscesses, or coughing, is asked to call Dartmoor livestock protection officer Karla McKechnie on 07873 587561.
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The charities involved are expecting more visitors to the moor when lockdown restrictions ease
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