Animal skin diseases may result from various etiological factors. Some of these may act directly upon the skin itself, or indirectly via the blood, the lymph or the nervous system. Many internal pathological conditions may be the primary cause of various skin manifestations thus explaining why skin diseases of animals have always been studied in internal medicine.
"Etiology and Classification of Animal Dermatoses,"
Iowa State University Veterinarian: Vol. 21
, Article 9.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol21/iss2/9