Toenails Falling Out?

Hello I have a ****zu which has moderate to serious back issues which impairs its mobile transportation at times. lately her toenails have fallen out and her underbelly is turning a dark bruised color? Just wondering what this is a sign of? thanks
bill

I would take your dog to the vet immediately. That doesn't sound good at all.

It is a sign that a vet visit is in order.