I know it is common for bitches to have diarrhea after whelping  especially if she has eaten the placenta.  I tried not to let her eat them all but she did wolf down a few and now has very runny explosive black stools.  She had her babies yesterday and is eating and drinking fine. Do I need to worry and should I be feeding her anything to try and help it?

Totally normal if they eat placentas, it will soon pass (literally), you could give her boiled rice and chicken or fish with plenty of the rice water if you want to firm her up a bit quicker but she will be fine

Thanks - very reassuring!

A bitch should be allowed to eat all Placenta's, it perfectly normal & natural for them to do so & has lots of goodness in them.

I also see it a natures laxative. They don't want to be pushing too hard to go after giving birth when they are sore so eating placentas makes everything pass so much easier.

Generally speaking it's not necessary for a bitch to eat more than a couple, if that, of the placenta.   In the wild, it sustains the mum until she can get back out hunting again.   It's not necessary in our domestic bitches and I never allowed mine to get into them.

Right now her system is under stress so being loose is to be expected, within reason and certainly immdiately following a whelping.