1.      Nairobi sheep disease

2.      nanukayami disease

3.      navicular diseaes

4.      Newcastle disease

5.      new duck disease

6.      Nicolas-Favre disease

7.      Niemann’s disease

8.      nil disease

9.     nodular worm disease

10.   nodular disease

11.   Nonne-Milroy disease

12.   Norrie’s disease

13.   Norum-Gjone disease

14.   nosema disease

15.   notifiable disease

16.   Novy’s rat disease

17.   oasthouse urine disease

18.   obstructive small airways disease

19.   occupational disease

20.   Oguchi’s disease

21.   Ohara’s disease

22.   oid-oid disease

23.   Ollier’s disease

24.   Ondiri disease

25.   Opitz’s disease

26.   organic disease

27.   Oriental lung fluke disease

28.   Ormond’s disease

29.   Osgood-Schlatter disease

30.   Osler’s disease

31.   Osler-Weber-Rendu diseae

32.   Otto’s disease

33.   overeating disease

34.   Owren’s disease

35.   ox-warble disease

36.   Paas’s disease

37.   Pacheco’s disease

38.   Paget’s disease

39.   parenchymatous disease

40.   Parkinson’s disease

41.   Parrot’s disease

42.   parrot disease

43.   Parry’s disease

44.   Patella’s disease

45.   Payr’s disease

46.   pearl disease

47.   pearl-worker’s disease

48.   peduncle disease

49.   Pel-Ebstein disease

50.   Pelizaeus-Merzbacher disease