Hi; I have an 11 year old female calico named sparks. For many years now I've noticed a brownish/blackish waxy excretion that builds up around a couple of her nipples. They coat the nipples and are fairly easy to pull off. There doesn't seem to be any skin irritation underneath so they don't seem to be scabs. I've had a couple of the vets at my hospital look at them and they don't seem to be concerned but they also don't seem to know what's causing it. Has anyone seen this before? She is somewhat overweight - about 12 pounds and other than this, has no skin or fur problems.