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Transmissible Gastro Enteritis, TGE

TGE is a very important and highly infectious disease caused by a coronavirus. The virus is killed by sunlight within a few hours but will survive for long periods outside the pig in cold conditions. It is very susceptible to disinfectants particularly iodine based ones, quaternary ammonia and peroxygen compounds.

Disease will persist in the farrowing houses over a period of 3 to 4 weeks until sows have developed sufficient immunity to protect the piglets.

In herds of less than 300 sows the virus is usually self eliminating provided there are good all-in, all-out procedures in farrowing houses and grower accommodation. In larger herds however the virus will persist in the growing herd because piglets at weaning, still under the influence of the maternal antibody, move into houses where the virus still persists. Once the lactogenic immunity in the sow's milk is no longer being taken in the pigs become infected allowing the virus to multiply. The pigs then shed the virus, contaminating the weaner rooms and infecting pigs being weaned after them. TGE can become endemic in herds in a mild form with high morbidity but low mortality.

This disease in the weaning and the growing pig is clinically indistinguishable from porcine epidemic diarrhoea. In small grower-finisher units the virus is likely to disappear from the population. In large finishing units in which susceptible pigs are being brought in frequently, the virus is maintained indefinitely in the population by repeated infection of the newcomers.

Symptoms

Weaners & Growers
  • When the virus is introduced into a finishing herd for the first time there is rapidly spreading, vomiting and a watery diarrhoea, eventually affecting almost all the animals.
  • Disease disappears spontaneously over a 3 to 5 week period.
  • Mortality is usually low.
  • The main effect on the individual growing pig is dehydration which is resolved in about a week.
  • Nevertheless the disease may increase the slaughter age by 5-10 days.
Piglets
  • In the sucking piglet the disease is very severe.
  • Acute watery diarrhoea.
  • Almost 100% mortality within 2 to 3 days in piglets under 7 days of age due to severe dehydration and electrolyte imbalance.
  • There is no response to antibiotic therapy.
  • The most striking feature is the wet and dirty hairy appearance of all the litter due to the profuse diarrhoea.
Sows
  • In acute outbreaks the most striking feature is the rapidity of spread.
  • Vomiting.
  • Diarrhoea.
  • Adult animals show varying degrees of inappetence and usually recover over a 5 to 7 day period.

Causes / Contributing factors

  • The virus is shed in large numbers in the faeces.
  • Pig faeces therefore are the major source of transmission either directly through the purchased carrier pig or indirectly through mechanical transmission.
  • Poor pen floors.
  • Poor pen hygiene associated with bad drainage
  • Poor hygiene procedures, between pens
  • Environmental contamination from one pen to another i.e. boots, brushes, shovels clothing etc.
  • Feeder pipes and feed bins. This is a high risk source for the spread of enteric diseases.
  • Dogs may shed the virus in their faeces for 2 to 3 weeks.
  • Birds and in particular starlings may transmit the disease.
  • Contaminated feed.
  • Continual use of buildings without all-in, all-out may perpetuate disease.
  • Continual purchase of naive weaners.

Diagnosis

The clinical picture in acute disease is almost diagnostic. There are no other enteric diseases that spread so rapidly across all pigs. The ultimate diagnosis of TGE must be made in the laboratory from the intestine of a fresh dead pig using fluorescent antibody tests (FAT's). Isolation of the virus is also carried out.

Porcine epidemic diarrhoea (PED) could give a similar picture but it would be less acute and with less mortality in sucking pigs.

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.