Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
The management of hematomes occurring in the external ear of dogs presents a difficult problem of treatment. Some authorities say the condition usually arises in dogs having pendant ears but the short pointed eared dogs experience this difficulty the most often in our practice. The condition is the result of trauma associated with violent shaking of the ears. The resulting trauma ruptures the subcutaneous capillaries on the internal surface of the ear and the extravasated blood collects separating the conchal cartilage from the skin as it rapidly forms a fluctuating subcutaneous mass. The fluctuating mass may occur at any region on the ventral side of the ear and may vary in size from less than a centimeter to several centimeters in diameter. The condition is usually spoken of as a hematoma but in rare instances the fluid may consist of only serum.
Norton, R. E.
"Hematoma in the Ears of Dogs,"
Iowa State University Veterinarian: Vol. 7
, Article 9.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol7/iss2/9