Described here is a case report about a lesion that started as a blister on the forearm of my Dachshund, "Bitsie." We did not pay extra to have it biopsied, so unfortunately I cannot report a diagnosis.
A lesion, or blister, developed where her harness buckle rubbed against the forearm just below the elbow. The lesion never healed (even after months without a harness), and almost daily it would burst and release blood (never pus or other fluids).
Of course I searched the Internet for information, but never found a matching description (many articles were consulted, but here is an example).
Below is a series of photos showing the lesion a few weeks before we had it removed:
Here is a photo after the blister had burst and she licked it clean:
The lesion was surgically removed by a veterinarian. Luckily it was in a place with ample loose skin and it was not connected to tissues deeper than the skin.
Now it is all healed up with hardly a scar!