Protocol: Collection of samples for Footrot investigation

INTRODUCTION

Dichelobacter nodosus is the causative organism of footrot. It is a slow growing, fastidious anaerobic bacterium.

Following this protocol will provide the best chance of confirming the presence of this organism. Culture of samples require up to 2 weeks incubation before they can be classified as positive or negative. If a sample is positive, it may take up to 3 weeks before the virulence result is known.

MEDIA PROVIDED:

  • Modified Stuart’s Transport Medium (STM) which has been labelled with an expiry date. Do not use media after the expiry date.
  • STM can be stored at 4˚C but must come to ambient temperature (15-25˚C) before use.
  • The media contains an indicator solution. Media that have turned deep blue in colour should NOT be used.
  • Only use media supplied by Gribbles Veterinary Pathology.

COLLECTION METHOD:

  • Select the sheep most likely to be infected, preferably early active cases. Five cases will be adequate for most investigations.
  • Collect a scraping with a clean dry swab from the moist interdigital area.
  • The creamy/white dead tissue seen in the interdigital or skin/horn junction area provide the best samples, especially in early cases.
  • For more advanced cases, take scrapings from the leading edge of the lesion.

INOCULATION:

  • Break off the end of the swab and push the tip containing the collected material beneath the surface of the medium to exclude any air. Screw the lid onto the STM vial (finger tight only).

TRANSPORTATION:

  • Submit samples in an esky with an ice brick within 24 hours of collection. Wrap the STM samples in bubble wrap so they are not in direct contact with the ice brick.
  • Refrigerate samples if they cannot be sent within 24 hours.

Due to the fastidious nature of the organism, delays between sample collection and receipt of sample in the laboratory will significantly decrease the chance of successful isolation of Dichelobacter nodosus.

Please contact Gribbles Veterinary Pathology on 1300 307 190 if you are concerned or have any questions.

Footrot in sheep and goats is a notifiable disease. There is a legal requirement that anyone who suspects or diagnoses a notifiable disease reports it immediately to their nearest animal health adviser or government veterinarian officer.