Contagious Porcine Pleuropneumonia
Contagious Porcine Pleuropneumonia is a highly contagious and often fatal respiratory disease, seen in weanlings, growers and finishers ranging from 6 weeks to 6 months. It also causes abortion in sows and will cause milder respiratory signs in pigs of all ages. It is endemic in the UK.
The presence of Actinobacillus in the lungs causes a fibrinous pleurisy and pneumonia.
It is a disease of acute onset in naive/ susceptable herds and can cause high morbidity and mortality (up to 50%).Carrier herds have some immunity, protecting from acute disease, where lesions are often subclinical, and deaths sporadic
The disease is transmitted by carrier pigs or new pigs brought into the herd and is spread by direct contact or aerosol transmission.
In acute outbreaks, pigs may be dyspnoeic, pyrexic or anorexic. There will often be presence of blood-stained froth surrounding nose and mouth. Cyanosis follows later along with a sub-normal rectal temperature; death will then ensue. Pregnant sows will abort.
In sub-acture outbreaks, some pigs will be found dead but others in the group may show varying degrees of exercise intolerance and respiratory distress.
Clinical signs especially if in the acute form are suggestive of this diagnosis as inlfuenza rarely causes mortality and does not primarily effect young pigs.
The post mortem findings will confirm the dignosis. These will include; haemorrhagic consolidation close to the main bronchi or the diaphragmatic lung lobe, which is usually localised. Necrosis and fibrinous pleuritis may also be visible. Lung scarring and pleural adhesions may have developed in recovered animals.
Samples can be cultured on chocolate agar and diagnosed by immunofluorescent or PCR-based techniques. The bacteria on the palatine tonsil may remain undetected by serological tests and swabbing, and can therefore cause an outbreak in naive pigs.
Treatment and Control
Antibiotics should be administered as soon as clinical signs are suggestive of the disease. Water and feed intake is usually very reduced so in-water or in-feed treatments are of little use and treatment should be administered parenterally.Prophylactic antibiotics may be used for in-contact pigs.
As a control mechanism, killed and polyvalent bacterin vaccines as well as a subunit vaccine are available. They are given as two injections, two weeks apart to pigs no younger than six weeks of age. The sow can also be vaccinated pre and early pregnancy to allow passive immunity to occur.
Isolation on farms using all in all out systems will also dramatically reduce signs of infection, although not prevent it. Hygiene should be improved by improving ventilation and avoiding chilling and overcrowding.
Cowart, R.P. and Casteel, S.W. (2001) An Outline of Swine diseases: a handbook Wiley-Blackwell
Jackson, G.G. and Cockcroft, P.D. (2007) Handbook of Pig Medicine Saunders Elsevier
Straw, B.E. and Taylor, D.J. (2006) Disease of Swine Wiley-Blackwell
Taylor, D.J. (2006) Pig Diseases (Eighth edition) St Edmunsdbury Press ltd