Special Veterinary Pathology

ACTINOBACILLOSIS

Synonym : Wooden tongue

Definition

• Actinobacillosis is a specific infectious disease of cattle and sheep caused by Actinobacillus lignieresi and is characterized by fibrosis of tongue

Etiology

• Actinobacillus lignieresi – Gram negative aerobic organism
• Cattle usually affected. Sheep are rarely affected

Incidence

• It is most common in cattle and worldwide distribution. It is usually of sporadic occurrence on individual forms
• Human infection of the disease has also been reported

Transmisssion

• Organisms are normally present in upper respiratory and alimentary tract
• Affects mainly soft tissues.
• Wounds and abrasions caused by foreign bodies are necessary for infection

Pathogenesis

• Organisms are present in upper respiratory and alimentary tract mucosa and infection to soft tissues occurs through wounds and abrasions caused by foreign bodies like thorn and awns
• Then organisms multiply and causes c hronic supppurative and granulomatous inflammation of soft tissues i.e. tongue

Clinical signs

• The organisms may infect jaw of cattle, but usually it invades the tongue, lymph nodes of the head, neck and thorax
• Tongue replaced by fibrous tissue and becomes hard, shrunken and immobile(Wooden tongue)
• It usually affects soft tissue and lymph nodes of the mouth and pharynx

Gross lesions

• Cattle
• More frequent in soft tissues than bones
• Spread to neighbouring tissue, lesions coalesce, forming a large nodules with central ‘Sulphur granules’ (Colonies of organisms)
• Spread is usually through lymphatics causing lymphadenitis and abscess.
• Tongue – Nodules which becomes indurated, rigid and it is referred to as
• ‘ Wooden longue’ - Diffuse sclerosing actinobacillosis
• Lung and other tissues – Smaller abscesses seen.
• Pigs - Lesions similar to cattle
• Sheep - Lingual lesions are not common; subcutaneous tissue of the head, nose, lips, throat, cheeks and submaxillary region revealed granuloma

Microscopic lesions

• Granulomatous reaction
• Surrounding a colony of organisms, club like structure (action of macrophage on the organism)
• It is encircled by neutrophils, histiocytes, giant cells, lymphocytes and plasma cells and is enclosed by fibrous tissue
• Spread to neighbouring tissue, lesions coalesce, forming a large nodules with central ‘Sulphur granules’ (Colonies of organisms)

Diagnosis

• Symptoms
• Pus from affected area (gram negative rods)
• Histological examination of lesion
• Agglutination test