Some 20 yrs ago I was in the reverse position.  Took heifer to vet that I had a bad feeling was a small pelvis after trying to put on the chains.  It was a Saturday afternoon late and had the young daughter with me she might been 7.  Tried to convince the vet to just pull it and we would be ok.  He said no way as her pelvis was not big enough for his wrist.  C was only door that calf was coming out.  Moma and the only baby she was going to have lived happily that day.  Daughter still talks about it.  Never dreamed it would have that kind of effect.  Glad I was wrong that day and the Vet made a good decision.