Arduino measuring high-voltage electric fence
You are talking about measuring 2kV to 10kV pulses, with about 1J to 5J of energy per pulse.
The maximum current may be very low, but the voltages you want to measure are very high, and will very probably damage your Arduino without proper measures.
You will at least need a voltage divider to reduce the voltage the Arduino sees to 5V (or 3.3V for some Arduinos) to be able to make a measurement with the Arduino's ADC.
The voltages are high enough to bridge a fair distance with a spark; they could well bridge a physically small resistor or the distance between two connections on your breadboard or PCB.
To be honest, I think you shouldn't go anywhere near such voltages with an Arduino, unless you know exactly what you are doing when preparing the signal for an Arduino's ADC pin.