Question about rat pup

I posted a while ago about Nutmeg's first litter. Well she had two surviving pups during week 1 but one began to look a little funny. He was darker than the other pup in coloration but his eyes were also really dark. Actually they were quite buggy looking under the skin and you could see the pupil clearly through the skin. It looked odd to me and I fed him off right away but I was wondering if anyone knows what that could have been. The other surviving pup is not affected by it. The surviving pup is an PEW (Pink Eyed White) male. I'm pretty sure I'm going to feed him off once he is big enough as I don't really need more males in my colony right now (only 2 females breeding, soon to be 3).

may have just been that the babie while in the mother was malnurished and didnt form correctly... just an assumption.

Maybe the reason the eye looked so much darker, even through the skin, was because that pup would have had dark colored eyes, while the other one had pink eyes.

Hard to know if there was anything wrong without having seen it.

Well yes the pup would have had dark eyes, but I mean, they were bulging. I have rat pinks now that I can tell are going to have dark colored eyes and they are normal eyes, not bulging at all. I guess we will never know. If her next litter consists of the same thing I'm going to discontinue breeding her.

Thanks for the replies everyone.