exterior growth

My dog has a growth on its midlower back left leg. The first inch is tubular about 1/4 inch. It then goes into a mass about the size of  a large acorn. The whole thing is dark brown and is just hanging off of leg. Any idea what this is?

                                                                                  Thanks
                                                                                                                       Terry

[Aleda M Cheng, D.V.M., C.V.A]

It may be an unusual skin tag, or a pedunculated mass.  

There are many different kinds of benign and malignant skin lesions so it would be in your dog's best interest to have the mass biopsied either by a needle aspirate, or by an excisional biopsy in which the entire mass is removed and identified by a pathologist.