These three photographs are from dogs. I hope you notice that this animal was necropsied from the wrong side. What side is that?
There are a host of abnormalities here. I see at least five. You might build a story or a differential list on the basis of the spleen or I suppose you might build one on the basis of the lung or maybe some other abnormality. You probably have trouble reaching a finite conclusion. Possibly the next slide will help you.
Spleen side of the animal is up. Spleen is very large and not dark purple enough to be severely engorged with blood. Dog is pale; a zonal liver lesion; lungs greyish, big and solid appearing. Check body lymph nodes. This is a lymphoreticular cell proliferative/infiltrative process. Could be neoplastic but in fact is caused by fungal infection.
The middle photograph is of another dog`s lung with a similar disease, maybe the same disease, and this picture suffers the problem that you can tell more about lungs with your eyes closed than you can with them open, unless your eyes are in the tips of your fingers. What did that mean? Do you think, based on looking at this picture, you might perceive the quality of the lung lesion? Give it a try.
The right photograph is another dog and the quality of this lesion is in the same family as the previous lesion. The etiologies, however, are different. Have a good look at this lung and work some more on what the basic lesion is and then think about a potential etiology.
The middle photograph is histoplasmosis; the right photograph is coccidioidomycosis. The appearance of the lung lesion is more dependent on host resistance/susceptibility than on the specific fungal agent. The greater the susceptibility, the more diffuse the lesion(s).
