Actinobacillosis

[Kvet Forum]

Etiology: Actinobacillus lignieresii.

Epidemiology

Organism is a normal inhabitant
of the alimentary tract.
Infection occurs through an abrasion of the oral mucosa or skin.
Site difference in sheep and cattle reflects
differences in risk associated with prehension of food.
Sporadic disease but outbreaks occur in herds/flocks where predisposing factors are present.


Risk Factors

The disease is usually sporadic, but multiple
cases in a herd and apparent outbreaks of the
disease can occur when animals graze abrasive pasture species or pastures with spiny awns and transmission may be enhanced by infected discharges contaminating these pastures or feeds.
A severe outbreak has also been reported in heifers fed on very dry, stemmy, tough haylage and in cattle fed wheat straw from a specific thresher that produced straw with sharp edges.


Clinical Findings

• Difficulty in prehension of food.
• There is excessive salivation and gentle chewing of the tongue as though a foreign body were present in the mouth.
• On palpation the tongue is swollen and hard, particularly at the base, with the tip often appearing to be normal.
• Nodules and ulcers are present on the side of the tongue, and there may be an ulcer at the anterior edge of the dorsum.
• In the later stages in which the acute inflammation is replaced by fibrous tissue, the tongue becomes shrunken and immobile and there is considerable interference with prehension.
• There may be visible and palpable enlargement of the submaxillary and parotid nodes.
• Local, firm swellings develop and often rupture with the discharge of thin, nonodorous pus.
• Inflammation and abscessation of tongue and draining lymph nodes in cattle and of lips in sheep.
• External trauma from abrasive materials in the environment is the usual initiating cause.

Treatment

• Sodium-iodide (as 10% or 20% solution)
(70 mg/kg IV, may be repeated after 7–10
days)

• Potassium-iodide (6–10 g per animal orally
every 24 h for 10 days)

• Procaine penicillin (44,000 IU/kg IM every
24 h for 7 days)