aggression after whelping

Question
I am dog sitting my son's basset hound while he is out of town working.  She whelped for the first time(wasn't breed intentionally) while he was gone. She seemed to do fine with the puppies but she has become very aggressive.  She has been around me a lot and has been here for a week, always friendly happy loyal dog.  The fist day she did fine, we touched the pups a time or two, not too much just enough to make sure they were ok. We have checked in on her numerous times.  We started putting the food bowl in her dog house because she wasn't coming out.  When we went to check on her she was very aggressive and tried to bite us.  She has another female in her pen that she was raised with.  We tried to separate them on the first day she whelped but that seemed to be very traumatic so we let her back in the pen.  Her litter mate doesn't mess with the pups and she doesn't seem to mind that she in the large pen with her.  We put separate houses in there but we just don't know what to do now that she has become so aggressive.  Any advise would be greatly appreciated.

Answer
Hi Cheryl

It's very important to take the other female out and leave the dam with her pups.  The female needs to feel her pups are safe and secure.

I would recommend that you take her to the vet and have her inspected.  She could have a retained placenta, stillborn pup, mastitis forming.  Although some dams will become protective of their off-spring, they typically won't turn mean without a reason.  And in this case I would think it would have to do with her whelp.

Good luck