So it's udder has fallen off?
That's not so silly as it sounds.
I've seen it many times in ewes with mastitis, where the infected udder becomes isolated from the surrounding tissue and sloughs away, leaving an area of apparently healthy looking tissue that doesn't heal over.
No idea whether something similar could have happened to your doe, but it would be interesting to know what the lymph nodes were like.
What do the edges of the skin look like around the wound? Fresh cut, or do they appear to be rolled under?
Either that or it damaged itself running after being shot (fence?), but if so it's managed to leave a substantial chunk of itself behind, which you would have seen.
It's not hydrostatic shock, whatever.