
How much more than normal are you feeding her? It
could be that you've increased her food too quickly. I've found with mine that for the first few days post-whelping that they eat only slightly more than usual, but the amount needed increases as the puppies grow and take more milk from her. At about three weeks, when I start weaning, the bitch will be eating about 4 times her normal, non-pregnant 'maintenance' quantity. It's
possible (not saying you are) you're feeding her too much and overloading her digestive system.