Title: Classical swine fever (Hog cholera) | The Pig Site
Headings: Classical swine fever (Hog cholera)
Classical swine fever (Hog cholera)
Background and history
Clinical signs
Acute disease
Sub-acute disease
Chronic and aberrant disease and persistent infection
Diagnosis
Post-mortem
Causes
Prevention
Vaccination
National eradication programmes
National preventative programmes
On-farm precautions
Treatment
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Content: Sub-acute disease
The early signs in growing pigs are similar but they progress more slowly and are less severe. Affected pigs may be ill for up to 30 days before they die. Chronic and aberrant disease and persistent infection
The virus can cross the placenta and infect the piglets in the sow's uterus. Sows that have been inadequately vaccinated that become infected, or sows which become infected with a virus of low virulence, may appear normal but give birth to shaking piglets many of which die. ( Note: there are also other causes of shaking or trembling piglets). If the virus crosses the placenta before the piglets' immune systems have developed they may be born apparently healthy although possibly weak and may grow on to be persistent carriers without at first showing clinical signs. They shed virus so they are a menace to other pigs. At several weeks or months of age they may develop typical clinical signs but these are likely to be milder, last longer and without the high temperatures. Virus that infects the piglets in the uterus may cause other effects, namely, death, mummification, abortion or the birth of weak piglets some of which may be deformed.