Without any 'gold-standard' requirement for testing and diagnosis, any system like this cannot be expected to be accurate. eg see;
"Concurrence between clinical and pathologic diagnoses in a veterinary medical teaching hospital: 623 cases (1989 and 1999)." J Am Vet Med Assoc. 2004 Feb 1;224(3):403-6. Kent MS, Lucroy MD, Dank G, Lehenbauer TW, Madewell BR.
-- there was disagreement between the clinical and pathologic diagnoses in approximately a third of the cases.
and
"Comparison of clinical and pathological diagnoses in dogs." Vet Q. 2005;27(1):2-10. Vos JH, Borst GH, Visser IJ, Soethout KC, de Haan L, Haffmans F, Hovius MP, Goedendorp P, de Groot MA, Prud'homme van Reine FH, van Soest IL, Willigenburg AH, van Woerden MA, Ziekman PG.
-- At necropsy 42 cases were diagnosed as neoplasia, of which 52.4% had been diagnosed clinically. As to infectious diseases 55.0% of these diseases diagnosed at necropsy had been diagnosed clinically. ie just under half the tumours and 45% of infections were not diagnosed until post mortem.
and an anecdote about reported diseases and disease reporting..
I was contacted by a person who said their dog had Addison's disease (hypoadrenocorticism). Only after much discussion did I learn that the dog had hypoadrenocorticism because his adrenal glands had been surgically removed (!).
sometimes you need to know more than the one word diagnosis in the report.