Changes

The disease usually affects weanlings '''6-10 weeks old''' when maternal antibodies wane but it can affect pigs of any age, particularly naive pigs introduced into a herd or through exposure to a strain to which there is little immunity. The stress of mixing, weaning and adverse environmental conditions are predisposing factors.

The disease usually affects weanlings '''6-10 weeks old''' when maternal antibodies wane but it can affect pigs of any age, particularly naive pigs introduced into a herd or through exposure to a strain to which there is little immunity. The stress of mixing, weaning and adverse environmental conditions are predisposing factors.

The disease occurs '''worldwide''', it is endemic in most herds but incidence of clinical disease in the UK is sporadic due to widespread acquired resistance. Increased prevelance has been associated with [[Porcine Reproductive and Respiratory Syndrome|PRRS]], [[Porcine Circoviruses|Circovirus]] and [[Swine Influenza|Swine Influenza.]]  

The disease occurs '''worldwide''', it is endemic in most herds but incidence of clinical disease in the UK is sporadic due to widespread acquired resistance. Increased prevalance has been associated with [[Porcine Reproductive and Respiratory Syndrome|PRRS]], [[Porcine Circoviruses|Circovirus]] and [[Swine Influenza|Swine Influenza.]]  

Mortality is high where there is no immunity, for example outbreaks in specific pathogen-free herds.   

Mortality is high where there is no immunity, for example outbreaks in specific pathogen-free herds.   

===Clinical signs===

===Clinical signs===

*Pyrexia

*Pyrexia

*Dyspneoa with abdominal effort

*Dyspnoea with abdominal effort

*Anorexia

*Anorexia

*Cough  

*Cough  

*Sudden death

*Sudden death

Clinical signs develop rapidly, the disease is often fatal within 2-5 days. The skin becomes discoloured, turning red to blue before death. Expressed lesions vary between animals.

Clinical signs develop rapidly; the disease is often fatal within 2-5 days. The skin becomes discoloured, turning red to blue before death. Expressed lesions vary between animals.

Survivors or those affected by the chronic form of the disease show less severe clinical signs of weight loss and depression, they become lame with arthritis, develop congestive heart failure, pericarditis or intestinal obstruction due to formation of adhesions. Pregnant sows may abort their fetuses.     

Survivors or those affected by the chronic form of the disease show less severe clinical signs of weight loss and depression, they become lame with arthritis, develop congestive heart failure, pericarditis or intestinal obstruction due to formation of adhesions. Pregnant sows may abort their fetuses.