Has anyone else had this happen to their dogs fur?

[SMarie123]

This has happened to my dogs leg, any ideas what it is? He is constantly at it!

My chihuahua has one. I asked the vet about it and was only told that if it gets better or starts to cause him pain when I touch it then something is wrong. Not an expert. If you're worried take your dog in for a quick check or call the vet's office and ask them about t