Background and history

Clostridia are large rod-shaped bacteria that also form spores and they persist in the environment for long periods. There are a number of different types. Disease in sows is associated with C. novyi, C. chauvoei and C. septicum. All these organisms produce toxins that may rapidly kill the host in a short period of time. The toxins are the main cause of disease not the bacteria but treatment must be given to prevent multiplication of the bacteria. The organism may enter the body through damage to the skin and underlying tissues and muscles. C. novyi spores also get carried from their normal habitat, the gut, to the liver where they may lie latent and inactive for long periods. Clostridia are also responsible for rapid decomposition of the body after death.

Clinical signs

C. septicum, often accompanied by the other two, causes malignant oedema, a form of gangrene, which is characterised by the appearance of painful and discoloured swellings.

Fluid and gas are often present in the tissues.

The most common disease in sows is associated with C. novyi which causes sudden death. This occurs when some unknown event cuts off the blood supply to an area of the liver which provides a perfect medium for the C. novyi spores to vegetate and rapidly multiply producing toxins. These severely damage the liver and kill the sow.

The course of the disease is extremely short and often the only sign is the finding of a good sow dead. A characteristic feature is the very rapid post-mortem changes particularly in the liver, which is full of gas and turns a chocolate colour. Gas bubbles may also be present throughout the carcass.

Diagnosis

Whenever sow mortality is more than 4% in the herd, death due to this disease should be considered. It is most important that post-mortem examinations are carried out as soon after death as possible (within two hours) because of the difficulty of differentiating between the lesions caused by C. novyi infection in the live pig and post-mortem changes.

Diagnosis is made by examining impression smears made on to a glass slide prepared from a cut surface of the liver and a fluorescent antibody test is carried out to identify the species. This disease can be a major problem in outdoor pigs and vaccination using either specific porcine vaccines or sheep vaccines containing the three clostridial organisms should be carried out. Two doses are given 3-6 weeks apart with a booster vaccination being given at each weaning time.

Causes

• Disease in sows is associated with C. novyi, C. chauvoei and C. septicum
• The toxins are the main cause of disease not the bacteria but treatment must be given to prevent multiplication of the bacteria.
• The organism may enter the body through damage to the skin and underlying tissues and muscles.
  

Prevention

Vaccinate all breeding stock and if necessary repeat the vaccination every six months.

Treatment

Vaccines are commercially available but it may be six to eight weeks before sows are fully immune.

• Clostridia are very sensitive to penicillin. In-feed medication using 200 grams to the tonne of phenoxymethyl penicillin can be used for 3-4 weeks to control acute outbreaks whilst a vaccination programme is established.
• Long-acting injections of penicillin given in anticipation of disease may help in the short term.