London is 3 1/2 and her belly is starting to get darker. I assume it's normal because London acts normal and it isn't sore at all, she still demands her belly rubs, haha.
I personally wouldn't worry about it. Everyone's skin changes as they age. If it's sore or she isn't eating or going potty I would take her to a vet though.
In my humble opinion, I would say it's ok
