Derry City and Strabane District Council have renewed an appeal for owners to keep their dogs under control.
The initial call out was made in February, reminding pet owners of their responsibility.
They say when a dog attacks or chases livestock on agricultural land it result in significant injury or suffering and in worst cases, death of the animals involved.
It is a particular concern for farmers during lambing season, as it can cause miscarriage.
The council also say that dog wardens have the authority to seize any dog, of any type and breed, suspected of being involved in worrying or attacking livestock, owners may be prosecuted for any offences and a court may order the dog to be destroyed.
