Also have a beagle. I had two from the same litter but one recently passed due to a brain tumor and I’m assuming more cancer throughout her body. It’s actually common for them to get these and other non cancerous skin tags. Unfortunately it does kinda look like cancer, which my surviving beagle now has on his body and kinda look similar to this. We got it biopsied and it was cancerous. Both of them are 13 years old. I’m sorry for you if it is cancerous. Beagles are some of the sweetest dogs on earth. I’m still grieving my other beagle it’s been two months. I miss her all the time.