A spirochete isolated from a case of severe virulent ovine foot disease is closely related to a Treponeme isolated from human periodontitis and bovine digital dermatitis.

The isolation of spirochetes from severe ovine foot disease has been reported recently by our research group. In this study we describe the preliminary classification of this spirochete based on nucleotide sequence analysis of the PCR-amplified 16S rRNA gene. Phylogenetic analysis of this sequence in comparison with other previously reported 16S rRNA gene sequences showed that the spirochete belonged to the treponemal phylotype Treponema vincentii which has been associated with bovine digital dermatitis and human periodontal disease. Further work is required to define the common virulence determinants of these closely related treponemes in the aetiology of these tissue destructive diseases.

Grading the lesions of ovine footrot.

Sixteen methods of grading the lesions of ovine footrot were assessed on the basis of the effect of the lesions on the humoral immune response of the host to a causative bacterium, Dichelobacter nodosus. Methods that allowed for qualitative and quantitative differences in lesion scores between sheep were the best predictors of host response, and methods that assessed the lesions in each of the eight digits were more efficient than methods that did not grade the digits within feet. Weighting the scores for lesions that involved underrunning of the keratin of the hoof provided the most powerful means of predicting host response. The correlations between host response and the more elaborate weighted scores were close to the highest possible among additive linear estimators. Total weighted footscore, which is the sum of the footscores of the four feet weighted for underrun lesions, is proposed as a simple and effective grading system for sheep with lesions of footrot. There was a significant association within sheep between the number of underrun feet and the severity of lesions in individual feet.