February 15-18, 2009 Washington State Convention Center Seattle ...

THE UTILIZATION OF HISTOPATHOLOGY IN AQUACULTURE RESEARCH AND THE
DEVELOPMENT OF A HISTOLOGIC LESION GRADING SCHEME
Kevin Snekvik*, Christopher Good, John Davidson, Carla Welsh and Steven Summerfelt
Washington Animal Disease Diagnostic Laboratory
Department of Veterinary Microbiology and Pathology
College of Veterinary Medicine
Washington State University
Bustad Hall, Rm 155N
Pullman, WA 99165-2037 USA
ksnek@vetmed.wsu.edu
While several parameters, such as overall mortality or grow rate, are typically evaluated during research experiments, histopathology
is often overlooked as an important tool in understanding the effect of various treatments, pathogen challenges or
environmental conditions on the examined species. In particular, histopathology provides a view of both the effect of specific
treatments on individual organ systems, for example epithelial cell degeneration in the gills or inflammatory cell infiltrates in
the liver, as well as providing a general assessment of the entire animal, such as muscle atrophy during anorexia, which few
other assays can provide. The response of the individual organs or the immune system can then be segregated into multiple
grades from minimal to severe to better determine the effect of the treatment. In a set of experiments utilizing rainbow trout in
recirculation systems we have included the histological evaluation of multiple organs and established a histopathological grading
scheme to evaluate individual organ systems as well as determine an overall “damage score” to each fish within a particular
treatment group. This has allowed a semi-quantitative assessment of disease between particular groups.
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