Actinobacillosis - Cattle

• "Wooden tongue"
• In cattle - very widespread in world, but rather sporadic, less common now than it was.

Clinical

• Seen in youngish animals in beef breed, especially sucklers on poor forage.
• Starts like foot and mouth disease - dull, salivating (if only one animal is unlikely to foot and mouth). - nearly always sporadic.
• ongue feels like a big lump of wood especially dorsal part of posterior 2/3rds.
• Small areas of ulceration are often found on side of tongue.

Pathogenesis

'Sulpher body' of Actinobacillosis (Courtesy of Alun Williams (RVC))

• Very similar to Mandibular Osteomyelitis ("lumpy jaw").

• Causal agent: Actinobacillus lignieresii (small gram -ve) gets into tongue via small abrasions.
  • Pathogen is very widespread in environment.
• Progressive disease - low virulence but high persistence so animal may stop eating and eventually die but can be treated.

Pathology

Fibrous Stroma - Cut Surface of actinobacillosis affected tongue (Courtesy of Alun Williams (RVC))

• If cut into tongue, substance of tongue changed to fibrous stroma with raised red nodules. (2-3mm across).
• This lesion is a pyogenic granuloma with central sulphur body.
• Can spread from tongue to other tissues e.g. retropharyngeal lymph nodes and palate.
• This type of lesion is caused by the host response to the pathogen, rather than directly a pathogen effect.

Other sites

• Occasionally can see generalised infections but more commonly spreads to local lymph nodes of alimentary tract.
• Organism can be inhaled causing actinobacillus pneumonia.
• Can affect rumen wall.
• In skin forms a neoplastic like mass in dermis.