Electric fences operate by sending a pulse of high-voltage electricity around an open-wire metal fence. In normal operation, where the system is properly earthed, an electric fence should not cause interference to television or radio reception.
When an electric fence is not working properly, the electrical pulses from it can sometimes cause interference to Freeview reception and to the radio, particularly DAB and AM, if the fence is close to your property.
Check the fence is the real problem by asking the owner to switch it off for a short period to see whether the interference stops. The owner should be prepared to co-operate with you and take reasonable steps to resolve the problem.