Calcium oxalate nephrolithiasis and tubular necrosis in recent metamorphs of Rana sylvatica (Lithobates sylvaticus) fed spinach during the premetamorphic (tadpole) stage.
Amphibians in the family Ranidae (true frogs) seem highly susceptible to oxalosis, particularly when fed a diet high in oxalic acid during the premetamorphic (tadpole) stage. The authors describe the mortality of 150 captive-raised wood frogs (Rana sylvatica or Lithobates sylvaticus) from oxalate nephrolithiasis and renal tubular necrosis caused by consumption of boiled spinach during tadpole development. Renal lesions were due to intraluminal transparent crystals which were birefringent under polarized light and were identified morphologically and histochemically as composed of calcium oxalate. Evidence of early fibrosis or squamous metaplasia, and a presentation at least 2 weeks after spinach consumption had ended, suggested a subacute course. Tadpole-feeding protocols should avoid plants with high oxalate content (eg, spinach and rhubarb leaves), and any episode of high mortality in captive amphibians along with nephrolithiasis should prompt an evaluation of the feed sources for material with high oxalate content.
Canadian Cooperative Wildlife Health Centre, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada mforzan@ccwhc.ca.
M J
MJ
Forzán
Department of Biology, Acadia University, Wolfville, Nova Scotia, Canada Biological and Geological Sciences, Department of Biology, University of Western Ontario, London, Ontario, Canada.
L V
LV
Ferguson
Department of Biology, Acadia University, Wolfville, Nova Scotia, Canada.
T G
TG
Smith
D000818:Animals; D002129:Calcium Oxalate / Q000009:adverse effects*; D007668:Kidney / Q000473:pathology; D007673:Kidney Cortex Necrosis / Q000473:pathology / Q000662:veterinary*; D007814:Larva; D053040:Nephrolithiasis / Q000473:pathology / Q000662:veterinary*; D011898:Ranidae; D018724:Spinacia oleracea / Q000737:chemistry*
D002129:Calcium Oxalate
Lithobates sylvaticus; Rana sylvatica; calcium oxalate; crystal; kidney; nephrolithiasis; spinach; tubular necrosis