When does this dark green/black discharge on my dog disappear?

My dog whelped yesterday and today she keeps discharging dark green fluid..they said its the placenta, when will this stop coz its stains everything

Take him/she to the ver that's serious

Since she whelped yesterday, both her and the pups should be at the Vet today. The Vet will give the Dam an injection of Oxytocin, and that WILL clean her out of all that retained placenta material. The Vet will also check out all the pups for any abnormalities such as cleft palates. Make sure you keep the puppies warm in transit to the Vet. When the pups are 3-4 days old, they can go back to the Vet to have their dew claws removed.

This is not good and you need to take her to the vet along with the puppies. There may be a retained placenta (you were supposed to count them as the pups were born so you would know) or even a dead puppy. A green discharge signals a problem, no matter what you've been told.