As in all electric circuits, current flow requires the establishment of a closed loop.
If there is no conductive loop, there can be no current flow. For a circuit
that involves the body of a cow, a two-point contact is required to establish
this conductive loop. The current must have a path into the cow and
another path out and back to its source.
Contact with a single point will not allow current to flow, and the cow
will not be exposed to stray voltage.
Stray voltage is a situational voltage experience resulting from the
presence of voltage gradients in and on the surface of the earth,
and between the earth and conductive objects connected to the earth.
A cow is exposed to stray voltage only when it is in simultaneous contact
with two points (surfaces) that have a voltage gradient between them.
