I was just in Cernaya Polana with a fully charged Cattle prod (Pristine, with pristine battery I started with) when a full gear suddenly showed up in front of me.
I hit him at least 6 times with the cattle prod when he was stood still and another three times later on (the guy was a lousy shot)
I've been attacked repeatedly with the cattle prod and I never went unconscious at all. I suppose this would only happen if you were hit in the head. This renders the weapon totally useless... as so many other items in the game, it isn't working.