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Vomiting, Wasting Disease, Ontario Encephalitis

This is caused by a coronavirus which is widespread in the pig populations of North America and Europe but clinical disease is rare. This is because although the virus can infect susceptible pigs at any age it only causes clinical disease in newborn piglets. Most sows have been infected and are immune. They pass their immunity to their piglets in colostrum which protects them through the vulnerable period.

There is a variation in virulence between strains resulting in two different disease syndromes. Both start at around 4 days of age, are sudden in onset and affect whole litters


Sows, Weaners & Growers
  • N/A
  • Huddled.
  • Hairy.
  • Vomit bright green-yellow vomitus.
  • Constipated.
  • In the typical vomiting and wasting disease syndrome piglets lose their ability to suck or swallow, become very thirsty and stand with their heads over water but are unable to drink.
  • They waste away, become severely emaciated and die.
In the typical encephalitis or brain infected syndrome they:
  • Froth and champ at the mouth.
  • Develop blueing of their extremities.
  • Abdomens become bloated.
  • Tremble.
  • Stilted gait which rapidly progresses to partial paralysis of the legs.
  • They lie down.
  • Go into convulsions.
  • Roll their eyes.
  • Die within four days of onset.

Causes / Contributing factors

  • Lack of immunity from sows to piglets via colostrum.


The clinical and pathological picture is diagnostic of the disease. If you open up their abdomens you will find gas in the stomach and intestine but no food, only some brightly coloured liquid. You will also see brightly coloured crystals in the kidneys. A blood test is available. There is no treatment.

Further Reading

Click on the links below to find out more about this disease, including treatment, management control and prevention information. The top link is the main article on this disease.