Thanks for the suggestions
It may have nothing to do with it.
Get ye a tester. Test before the pole and after the pole. That will give you an idea if the pole is the cause or not.
There are so many things that can make an electric fence not work. If the ground is not moist enough near the grounding rod system is one of the most common issues. Lack of a good ground there will make the whole fence not work correctly.
Like I posted before, go to the web site of several of the electric tape manufacturers. They have pretty comprehensive installation manuals that include 'do this' and 'do not do this'.
Though I think a good fence is a pretty important thing. I think you are being some what dramatic in saying it is imminent that the horses will get out any moment.
Edit to add - quick type into Google got me This. (I admit, I did not read the whole thing, but it looks to have lots of good information.)