So, what does the term "moondance" bring to mind? Oddly enough, for most SL Goreans, it implies something fatal. Yet nothing in the books supports this view.
Some of us have debated this, and come to a few conclusions we think are pretty logical, given context clues in the books.
A moondance serves two purposes. First, it provides a sexual outlet for panther girls, but it's only the first step of the process. The second thing it does, usually, is breaks the captive male, preparing him for slavery. It's a male, they're supposed to be the stronger ones in Gorean society, so it would take more drastic measures to prove to them they too can be mastered.
Does it always work? Of course not, just as slapping a collar on a panther girl does not always a slave make. Both views are backed up by comments in the books. Tarl himself discusses how "not everyone takes to the collar" in Hunters. Hunters is also where we find the example that not all men break, in the character Rim. He was clearly captured, bearing the degredation stripe to prove it, yet while he behaves somewhat humbly until freed, it's obvious he's not broken.
A moondance isn't the only outlet, as the books mention how men are kept as slaves until the panthers tire of them, then sell them. So clearly, the moondance itself is not the only sexual outlet for panthers.
I suppose I can see where the concept that it means death for the captive male comes from. In a male-dominated society, being broken and forced to admit you've been bested by women would be a 'death' of your place as a Gorean man. Don't worry though, it's not really fatal...