Sometimes when the smears are prepared from collected blood of healthy animals, The WBCs seem to be lysed. What could be the error in collection or smear preparation?
One thing that comes into my mind is that the blood has Streptococcus pyogenes, this particular strain expresses streptolysin-s on its surface which kills the white cell.
My thought is not as interesting as Guy's, but it may be possible that is just the way the smears were made. Sometimes if you press too hard or at the wrong angle then you get very few cells and even less WBC on the slide. Try to make sure that as the smears are prepared that the smear goes gradually from a thicker application on one end of the slide to the thiner 'smear' at the end.
You see Carson,
I went to the most dificult thing you went directly to the most simple thing.
Thats the way to go.