The National Trust and West Mercia Police have recorded a number of problems involving dogs this year at Carding Mill Valley, Church Stretton.
These include attacks on sheep, dogs going missing and even suffering mysterious 'sudden dog death' after being let off the lead.
The National Trust and the police today issued a plea for dog walkers to be responsible after incidents which also include dogs disturbing the nests of struggling bird populations in the conservation area, and dog fouling on paths that are used by 30,000 school children a year.
Peter Carty, countryside manager for the National Trust in South Shropshire said: "We've had sheep with throats bitten bleeding to death – it can get pretty gruesome. It's an annual occurrence but we feel it is on the up."
He said dogs that were not kept close or on a lead often went missing for an hour or more, during with time they could be worrying or even attacking some of the thousands of sheep on the Long Mynd.
If that was not enough reason to keep dogs close and under control, he said, they had had a couple of incidences of 'sudden dog death' this year, apparently after dogs drank heavily from open water in hot periods. He said local vets had suggested it was down to blue-green algae, the Environment Agency found none in Long Mynd ponds.
"It's not fully explained," he added.
Visitors are asked to obey the new 'Carding Mill Valley and Long Mynd Code of Conduct' which includes keeping dogs in sight and on a lead if not used to livestock.