RED DEER – A swine disease that knows no boundaries is being found in herds throughout the world.
Only a small percentage of animals ever shows signs of circovirus, but if swine are stressed, the disease can set in, said veterinary Frank Marshall, a member of Western Swine Health Associates and owner of Marshall Swine Health Services at Camrose, Alta.
“We know it leaves the immune system compromised,” he said at the Red Deer swine technology workshop Oct. 25.
“It appears there is probably no herd left on earth that is free of circovirus.”
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Porcine circovirus 1, or PCV1, was first identified in 1974. It did not cause disease but was found in tissues cultured for other disease diagnoses.
In 1991, veterinarians noticed nursery pigs were losing body condition and developing breathing problems and enlarged lymph nodes. Some also had diarrhea, paleness and jaundice. It was not until 1997 that porcine circovirus 2 was isolated and it has since been found in pigs worldwide.
PCV2 leads to the destruction of white blood cells known as lymphocytes that are needed in the pig’s immune system. The lymph nodes and tonsils have large numbers of lymphocytes.
“Everything we deal with in pigs, you can look in that tonsil and find it,” Marshall said.
A pig’s tonsil is a raised gland about the size of a loonie and it can harbour bacteria and viruses in microscopic pockets.
Exactly how this virus transmits disease is not well understood, and since there appear to be other diseases present with it, a complete post-mortem is necessary to identify it.
Vets report seeing a range of symptoms and autopsies reveal circovirus lesions throughout the body. Large skin lesions that start on the flanks are often seen. An examination of the kidneys and livers shows white scarring. The lungs are affected and won’t collapse so the pig could die of heart failure.
Small and large bowel disease may be present. The abdomen may be distended and the problem could be mistaken for ileitis.
For example, the nursery diet may not be correct and the animals may develop ulcers and the virus sets in. Antibiotics have little effect if circovirus is the underlying cause.
“Right now we have 10-20 percent mortality in nurseries due to a variety of different entities, all PCV 2 related disease,” he said.
There is no vaccine, so good hygiene and management are needed to minimize the problem.
Pig to pig contact should be limited by the use of solid pen dividers. The same groups should be weaned to finish and an all in, all out flow is recommended.
Other suggestions include:
- Avoid overcrowding.
- Ensure appropriate ventilation and temperature.
- Ensure the correct diet for the age of the pig. Increase access to feed and water for weaners.
- Treat any existing disease in the barn and quickly remove sick or dead pigs.
- Clean and disinfect between each group. Use hot water washes. Allow areas to dry and disinfect with products like Virkon or Synergise.
- Use new needles and disinfect instruments between litters.
- Ensure piglets receive adequate colostrum within six hours.
- Stop cross fostering after 24 hours of age.
- Ensure piglet comfort.
- Keep all vaccinations up to date.
