Improved laboratory diagnosis of ovine footrot: an update

Ovine footrot is a complex clinical disease syndrome primarily resulting from infection by the anaerobic bacterium Dichelobacter nodosus. In order to aid clinical diagnosis, various laboratory tests based on the detection and measurements of phenotypic properties of D. nodosus have been developed for genus-specific detection as well as virulence determination. However, these tests are generally time-consuming, and tend to be variable with external factors that affect the growth and metabolism of the bacterium. A new generation of diagnostic reagents, such as monoclonal antibodies, gene probes and polymerase chain reaction, has been developed recently. Preliminary assessment of these reagents has shown potential to vastly improve the laboratory identification and determination of the virulence of D. nodosus. It is important that these new reagents are vigorously assessed against existing laboratory tests, such as the elastase test and gelatin gel test, prior to their adoption for the routine diagnosis of footrot.