Actinobacillosis - Cattle

Also known as:

Wooden tongue

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

Description

An infectious disease caused by the gram-negative coccobacilli Actinobacillus lignieresii. Characterised by inflammation of the soft tissues of the head especially the tongue and pharangeal lymph nodes of cattle and sheep. The Causal agent is widespread in the environment and part of the normal flora of the gastrointestinal mucosa. It gains access to the tongue via small abrasions. It can be a progressive disease of low virulence but high persistence so the animal may stop eating and eventually die if not treated.

Signalment

Occurs in cattle and sheep of all ages but particularly seen in young beef breeds especially sucklers on poor forage.

Diagnosis

A diagnosis can be made on history and clinical signs.

Clinical Signs

Often begins like foot and mouth disease. Animals are dull, have difficulty masticating, are inappetent and salivate profusely. The tongue is inflammed, hard swollen and painful with small areas of ulceration along its sides. Often the tongue is described like a lump of wood hence the name and may increase in size by up to 50%. In contrast to foot and mouth cases are nearly always sporadic.

Occasionally generalised infections occur and the bacteria may affect soft tissue anywhere in the gastrointestinal tract including the rumen, reticulum and oesophageal groove. Additionally a cutaneous form of the disease has been reported where ulcers and nodules are present in the subcutaneous tissue containing yellow-green pus.

Pathology

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

The tongue is changed to fibrous stroma with raised red nodules (2-3mm across)along the surface. This lesion is a pyogenic ganuloma containing large numbers of the bacterial rods which look like sulphur granules. This type of lesion is caused by the host response to the pathogen, rather than directly a pathogen effect.

Small granulomatous lesions containing 'sulphur granules' of large numbers of gram-negative rods

Treatment

Antibiotics are effective and streptomycin is recommended Intramuscularly for 10 days. Animals that do not respond to treatment in two weeks should be slaughtered.

Prognosis

If treatment is initiated early it is often successful however if treatment is delayed beyond 2 weeks the prognosis is much poorer.

References

Andrews, A.H, Blowey, R.W, Boyd, H and Eddy, R.G. (2004) Bovine Medicine (Second edition), Blackwell Publishing