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
On Aug. 12, 1952, a Hackney pony stallion was admitted to the Stange Memorial Clinic for a skin examination. At the posterior part of the neck, adjacent to the shoulder, was a raised, hairless area about 3 by 5 inches which contained several secondary nodules about the size of a marble. The skin of the area seemed to be abnormally thickened and it was more deeply pigmented than the unaffected skin. Just posterior to the olecranon at approximately the eleventh rib, on both sides of the animal, were solitary, raised, hairless areas about one inch in diameter. These appeared to be of the same nature as the larger area on the neck. No signs of pruritis were observed.
Gamble, Robert E.
"Microfilariae in the Skin of the Horse,"
Iowa State University Veterinarian: Vol. 15
, Article 13.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol15/iss1/13