The Incidence of Interdigital Skin Diseases in Flocks of Sheep Free of Virulent Foot‐rot

Abstract

1 B.V.Sc., Dip.Bact.

Risk factors associated with the prevalence of interdigital dermatitis in sheep from 1999 to 2000

“…Interdigital dermatitis is considered necessary for footrot to occur, because Dichelobacter nodosus , the causal organism of footrot, requires F necrophorum to invade the foot (Roberts and Egerton 1969, Thompson and others 1995); the two organisms then behave synergisti— cally, possibly in association with spirochaetes, to invade and underrun the hoof horn (Beveridge 1941). The severity of footrot depends upon the strain of D nodosus (Stewart and others 1986) and mildly pathogenic strains can cause footrot that is clinically indistinguishable from interdigital dermatitis (Parsonson and others 1967, Morgan and others 1972, Laing and Egerton 1978, Stewart and others 1986). In Great Britain, most farmers treat interdigital dermatitis by footbathing the lambs or the whole flock in 10 per cent zinc sulphate or 3 to 5 per cent formalin, or by applying topical foot sprays to affected sheep.…”

“…However, benign footrot may produce clinical signs indistinguishable from interdigital dermatitis (Parsonson and others 1967, Morgan and others 1972, Laing and Egerton 1978, Stewart and others 1986). Even virulent strains of D nodosus may initially cause lesions similar to those of interdigital dermatitis (L. J. Moore, unpublished observations), and they are likely to depend at least partly on the level of treatment and control on the farm.…”