Histological
And Ultrastructural Lesions Associated With Chronic Diarrhea In Arctic CharAlicia C. Noble1, Michael M. Garner2,
and Robert W. Nordhausen3 1Freshwater Institute, P.O. Box
1889, Shepherdstown, WV 25443; 2Northwest ZooPath, 18210 Waverly
Drive, Snohomish, WA 98296-4815; 3California Animal Health and Food
Safety Laboratory, School of Veterinary Medicine, University of California,
Davis, CA 95616. Arctic char (Salvelinus alpinus) cultured in a
recycle growout system at the Freshwater Institute were diagnosed with chronic
diarrhea. The number of fish affected
was estimated at over 50% and ranged from 800 grams to 1.6 kilo. Histology revealed severe granulomatous
gastritis with mineralization occurring within granulomas and in the collagen
of the submucosa and smooth muscle of the muscular tunic. Present also was mild to moderate
proliferative colitis, hepatic lipidosis, and mild non-suppurative
serositis. Electron microscopy of the
stomach revealed that cytoplasmic structures in the macrophages and
multinucleate cells, interpreted by light microscopy as possible infectious
agents, represented phagolysozomes, some with central mineralization or compact
membranous swirls. These were
interpreted as the early stages of the mineralization process. The most recent sample taken had
histological changes that were consistent with ongoing inflammation throughout
the intestinal tract. Severe
chronic/active transmural enteritis and severe granulomatous gastritis with
mineralization were observed. Electron microscopy of the intestine is
pending. Differential diagnoses and
possible mechanisms to explain these findings will be discussed.
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