Microscopic diagnosis from frozen canine tissues.

Frozen tissues were studied microscopically to determine their value for diagnostic purposes. Sections were taken from lung, liver, kidney, small intestine, and brain of ten diseased dogs that died or were euthanatized. Some tissues were frozen, held for two or seven days, and then formalin-fixed. Tissues that were formalin-fixed immediately served as controls. Freezing changes such as transudate, cell shrinkage, fractures, hemolysis, and hematin formation were a nuisance, but usually did not prevent making a diagnosis. Viral inclusions, microfilaria, fibrosis, and intestinal bacteria remained distinct.