Can I go near an electric cattle fence?

You don't need to give up cattle rustling if you have an ICD. Both line powered and battery powered electric fences pose low risk because they are energized for a very short time about once a second. If you accidentally touch an electric cattle fence, the momentary shock will be startling but it will not permanently damage your ICD. The shock may temporarily prevent the pacemaker portion of the ICD from sensing a slow heart rhythm.