The Mama Dog just died. :(
She must have had some complications from giving birth, Tammi said she was behaving somewhat weird even before she disappeared, but it seems like her condition worsened a lot during the past day. A vet is coming over this evening, but I suppose even if he had come earlier today it would have been too late to save her. Apparently she moved into some small doghouse in the neighbourhood and just laid down to die. I hope she wasn't in too much pain in the end, but she probably was. I feel really bad about this and not being there, able to help Tammi with the puppies and saying goodbye to the Mama Dog. Bleh. :/
UPDATE: The vet said she died from a tick, probably got infected just before giving birth. One of the puppies is really weak now, Tammi is getting some proper milk from the vet tomorrow afternoon.