Letters to the editor

Abstract

Extract

Sir:- Periodontal disease of the incisors (PD) is very commOn among hill sheep in Otago and Southland.(4) (5) The characteristic clinical signs are loosening and loss of permanent incisors with, frequently, incisor lengthening and protrusion in front of the upper dental pad. In the late '60s and early '70s, W.L. Porter(5) studied PD extensively. He found that the feeding of winter root crops exacerbated the condition, but possible primary causes such as selenium deficiency, lack of dental exercise and dietary oestrogenism were tested with negative results. The cause of the disease remains unknown. Porter however considered that ‘excessive intake of carotene by sheep grazing rapidly growing pasture may be aetiologically important through an effect on bone salt metabolism’.