If you do put up electric fence make sure there are signs on it at regular intervals as they are required by law. Also beware of theft of battery/charger in some places or even vandalism of the fence as some walkers dont like electric fences, make sure path is wide enough.
Would avoid signs other than a reminder to keep dogs under close control as livestock in field as wording suggesting the animal in field might be a risk is deemed to be an attempt to discourage walkers from exercising rights to use footpath.