My dog is hiding one of her puppies

Question
Hi. I have a 2 year old Rottweiler x Border Collie. She recently just had her very first litter of pups. A whole 7 of them! She has tried hard being a good mum but her in experience shows and due to lack of milk I am having to bottle feed the pups in conjunction with what she is doing with them. The puppies are nearly 2 weeks old now and the vet said they are doing really well and is amazed they have all survived. However the mum has started to hide (bury one of the smaller pups and I am really worried she may kill it accidently. This morning I found it burried under my blanket on my bed, then later in the after noon I heard it crying and I went in to my room and she had some how rolled it up in a sheet that I have on the floor for her just in case of accidents and it couldn't get out. I'm scared she is going to suffocate it. Why is she doing this? And should I take the pup away from her? It's the only one she is doing it to yet it isn't the runt of the litter as I have been told with runts the mother will sometimes reject them. She has been good with them up until now. Can you give me any advice as towhy she would be picking this one out and doing this to it? Thanks
~Sarah~

Answer
Sometimes dogs know things are not "right" about a pup, that we don't get. I'd manage the situation so she doesn't have the opportunity to "hide" the pup, if you want to try to save it. Let her in to feed them, but not keep her with them full time. And I hope you will have her spayed. There are a lot of mixed breed dogs already out there who need homes. Has she been eye checked, hips checked? What about the sire? Will you have a home for any of the puppies who fail in their new homes?