I had two female rats who I had raised up together have their first litters. After the births they did tussle sometimes (before they had been just fine :/ ), probably due to being protective of their babies. They also stole one anothers babies all the time.

Today though (7-10 days after birthing), I decided to give both litters to the older experienced females to foster. I noticed, while cleaning the cage, that about half of the babies had nips on them that were healing! I just put one down who had a massive chunk taken out of its head that was still alive and had the wound healing

It was really disturbing to say the least. I think the moms may have fought over babies or were just overly rough.

I hope the babies make it, they all seemed underfed as well. I've decided to put down the two females responsible.