Lost a fist calf heifer today

[greyhare]

I thought maybe someone here might have a clue as to what could have happened.
This morning a first calf beef heifer of ours died. Last night she was fine and normal on all accounts we could see. We drove them into their night pasture, in the barnyard. This morning, she was acting as if she was going into labor. She was due next month, AI breed. She was a black baldie and we breed her to a black angus bull who threw small calves. She had made up a nice udder and there was a clear mucus discharge. It was weird, so I called the vet as soon as I noticed her. She was getting up and moving around the pastures, then laying down again and she did srink when we offered her water. From the time I called the vet at 8:30 am she acted like she was in hard labor. By 11 am she was dead.
The only odd thing I noticed was that she was drooling a bit and her flanks were quivering.
Does anyone have any idea what could have went wrong? We are crushed, this was my sons first heifer to calf and his start on his own herd. He has already raised his first beer steer and was so proud when we put it into our freezer.

Thanks Trace

 

[hillsdown]

What did the vet say ?

 

[greyhare]

She died before the vet got to our place. She was dead in 2 1/2 hours after we called them. We've never had an animal go down like this before. She seemed to be in labor and we just expected her to abort the calf. My husband got a sleeve on and went inside to check her to see if the feet or head where anywhere near. She was very tight, not dilated as expected. He only felt the sac.
I was hoping the vet would have made it in time. After talking to a vet tec and out butcher, slaughtering was not recommened. I didn't bleed her out in time and the blood just had pooled on the entire side. By the time I reached the renderer, she was not longer usable. We buried her.
Weird was that when she was still alive, parts of her body seemed cold for a hot day. Her brisket and flank areas were cool to the touch.