Robinson M
J Comp Pathol. 1985 Oct;95(4):489-98. doi: 10.1016/0021-9975(85)90019-2.
An outbreak of periodontitis and oro-nasal fistulation in rats in a routine long-term bioassay is described. There was strong circumstantial and pathological evidence that the lesions were caused by long pointed food fibres present in an expanded diet which was fed as a powder.