cattle tail loss

[lyn white]

Has anyone seen this problem. I had a cow lose its tail. It started with the tail swelling up from the base down to around 1/3 of its length. The tail appeared paralysed. I don't know if this was due to the swelling or pain or was an actual nerve problem. Next the lower 2/3rd of the tail died and went stiff as if you had placed an elastrator band on it. This then dropped off and the remainder of the tail regressed. It is as if the bone dissolved, because as the tail shortened there was never any sign of bone. The tail ended up healing up at around 5inches in length. There was no obvious sign of injury/breakage. The tail swells to 2-3 times it normal size and appears to ooze droplets of fluid. I'm guessing ths fluid is a sign of the pressure that the tail is under due to the swelling. The cow is now fine. At no time did she appear ill. She didn't go off her food or appear unwell at any stage. This was around 5mths ago.
Today another cow has come in with a swollen, paralysed tail. Can anyone give me an idea what is causing this. The vets that I have spoken to don't seem to have any idea what it is. One person I spoke too has seen a similar thing in Charters Towers.
Our cows are white Brahman, living on mostly forest pasture in far north Queensland