Background and history

Actinobacillosis is caused by a bacterium called Actinobacillus suis or sometimes Actinobacillus equuli. It usually only affects piglets. The first of these is present in most herds and lives in the tonsils of older pigs, particularly sows. It may enter the piglet via the respiratory system or via cuts and abrasions. It occasionally produces a septicaemia, that is, it invades and multiplies in the bloodstream and settles out in various parts of the body, particularly the lungs and the joints. Here it produces multiple small abscesses. During the acute septicaemic phase of the disease sudden death is often the only symptom.

The disease has become more prevalent with the advent of PRRS, particularly in piglets one to three weeks old. Occasional disease may be seen in pigs up to 16 weeks of age. It is not a common disease.

Pigs with meningitis, acute E. coli infection, erysipelas, clostridial diseases and pigs that have been lain on can produce very similar symptoms.

Clinical signs

Sows

• Rarely applicable.

Piglets

• Sudden death.
• Discoloration of skin (blue).
• High fever.
• Coughing.
• Pneumonia.
• Skin lesions (not to be confused with erysipelas).
• Arthritis.
• Lameness.
• Septicaemia.

Weaners and growers

• Symptoms as for piglets
• Rarely seen.

Diagnosis

In herds with a history of sudden death post-mortem and laboratory examinations are needed to demonstrate characteristic lesions and the presence of the organism.

Causes

• It can be precipitated by PRRS.
• Teeth clipping.
• De-tailing.
• Scrubbed knees from poor concrete.
• It may enter the piglet via the respiratory system or via cuts and abrasions.
• It occasionally multiplies in the blood stream and settles out in various parts of the body, particularly the lungs and the joints. Here it produces multiple small abscesses.

Prevention

• Assess the significance of the causes listed above, and address accordingly.
• Where there are rough concrete floors it may help to brush these over with lime wash containing 28ml phenolic disinfectant to 4.5 litres of lime wash.

Treatment

• The organism is sensitive to most antibiotics but in particular injections of ceftiofur at 3mg/kg, amoxycillin or ampicillin at 5mg/kg or procaine penicillin at 1ml/20kg.
• Other antibiotics that can be used include OTC, lincomycin, cephalexin and trimethoprim/sulpha.
• In persistent outbreaks, if the appearance of the disease is predictable then preventive measures can be taken by giving long-acting preparations of the above medicines to all litters over a period of 3 to 4 weeks, after which the preventative medication then ceases and the situation is further assessed.
• In-feed medication with phenoxymethyl penicillin at 200g/tonne to the sow for the first 3 weeks of farrowing has proved successful in problem cases.