A lady sent me this pics wanting my opinion. No rads.The vet don't know what could be that.Perhaps coronitis,perhaps infection in the carthilague. (spanish Gabarro).At least they are a interesting pics.
I dont know to be honest. Could be poor hygene. It is a symptom of other conditions and they can be historic by the time the cellulitis comes along. But make no mistake you can shoot them if you do nothing.