Actinobacillosis

Synonym: Wooden tongue

• It is sporadic chronic infectious disease of cattle and sheep.
• It is characterized by the inflammation of tongue and soft tissues around the neck, head, oral cavity, pharyngeal lymph nodes, oesophageal groove and nasal cavity.

Etiology:

• Actinobacillus lignieresi
• Small, non-motile, gram-ve rod
• Organism grow singly or in short chain; produces sulphur granules.
• Organism may show bipolar staining character.
• It can be killed easily by usual disinfectants.

Epidemiology:

• It is worldwide in distribution.
• It is sporadic in nature.
• Cattle, buffalo and sheep are the susceptible animals.
• Younger animals ranging from 2-5 years of age are more susceptible.

Transmission:

• Disease is spread through infected discharges.
• Through contaminated pastures.
• Through contaminated feeds
• Infection of soft tissues occur through wound and abrasion caused by foreign bodies like sharp objects
• Through injury of oral mucosa due to abrasive feedstuffs, plant awns
• Eruption of permanent teeth of calves creates environment for bacterial proliferation
• Ectoparasites may play some role for cutaneous Actinobacillosis.

Pathogenesis:

Clinical Findings:

1. Cattle:

• Tongue is grossly affected and it may appear as wooden tongue.
• Drooling of saliva and difficulty in mastication
• Tongue is protruded, swollen and hard.
• Ulceration at different parts of tongue
• Intermandibular space is swollen and hard
• Enlargement of submandibular lymph nodes
• Pussy discharge from open abscess
• Interference in respiration and loud snoring sound is produced due to retropharyngeal involvement.
• Formation of subcutaneous nodules and discharge from them is seen.
• Generalized lymphadenopathy. Lymph nodes are often painful and pus discharge from them.

2. Sheep:

• Tongue is not the usual target organ. Lesion occur in the lower jaw, face, nose in cutaneous fold extending from lower jaw to sternum.
• Lymph nodes are affected and yellowish green pus containing granules discharges
• Bilateral nasal discharge from nasal mucosa
• Infected sheep dies due to inanition.

PM Findings:

• Formation of granulomatous tissues in the affected parts.
• On incision, greenish yellow firm, nodule and abscess of various size are exposed enclosing caseous or purulent masses.
• Pus is thick, mucoid, greenish yellow and odourless.
• Pus contain sulphur granules which appear as sand.
• Lymph glands are soft-yellow or orange colored.
• Granulomatous tumors develop containing characteristic granules.
• Granulomatous abscesses are mostly observed in muzzle, tongue, lips, submandibular and parotid glands as well as cervical areas.

Fig: Actinobacillus pleuropneumoniae infection, lung lesions, pig

Fig: Actinobacillus equuli infection, kidney and lung lesions, foal

Fig: Actinobacillus lignieresii infection, lung and heart lesions, cow

Diagnosis:

• Based on clinical signs
• Examination of granules
• Identification of organism; club-like structure
• Pus of Actinobacillus contain granules (rosettes) which are less than 1 mm in diameter and smaller than granules of actinomycosis
• Stained pus smear reveals gram-ve coccobacilli

Differential Diagnosis:

• Actinobacillosis of soft tissues particularly lymph glands may be confused with tuberculosis. Tuberculin test is advised in suspected cases.

Treatment:

• Surgical drainage of the abscess should be done and dressing should be done with iodine.
• Lugol’s iodine may be injected at the site of lesion.
• Iodine may be fed orally. Dose for cattle; 10gm/1000 lg b.wt orally daily for 2-4 weeks
• IV injection of sodium iodine may be made @70mg/kg, b.wt. It is repeated after 7-10 days
• Antibiotics like streptomycin sulphate may be given @5gm/day for 3-5 days.

Control Measures:

• Disease is zoonotic in nature. So, care should be taken while handling animals.
• Avoidance of coarse feed, coarse pasture & penetrating plant awns.
• Skin wound should be treated timely.
• Control of Actinobacillosis is best achieved by early recognition and prompt treatment of cases.
• Isolation of animals or disposal of dead animals with disease is recommended.
• Treated animals should be observed regularly so that relapses can be prevented.