
Many yrs ago I had a bitch who suffered from eclampsia which, of course, is life threatening. This was her 2nd litter, which I planned would be her last. She had a mistake litter a year later , no probs at all. She had no supplementary feeding (because I didn't know she was in whelp until she was 7 wks!) & whelped 5 pups (4 with the planned mating)
She was fed exactly the same for all 3 of her litters - the important thing is to be aware of the signs - which aren't always what the books say! I just knew she wasn't "right".
Sometimes, it just happens.
I think your vet is right - but not about the Hills!