A correctly made blood smear which is properly stained and competently observed has been called the single most valuable laboratory examination in medicine. Not only is it simple to perform, but it also plays a vital role in screening patients, in establishing differential diagnoses, and in following the history of a disease and the effect of treatment.
Hoppe, Bruce R. and Lassen, E. Duane
"Blood Smears and the Use of Wright's Stain,"
Iowa State University Veterinarian: Vol. 40
, Article 10.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol40/iss3/10