BANFF, Alta. – Brent Jones saw three types of pigs when he first discovered circovirus in his hog veterinary practice.
He called them the walking dead, the survivors that were set back five or six weeks but managed to live, and those with no apparent symptoms.
“You would have individuals that were totally destroyed pigs coexisting with pigs that seemed to have no issues whatsoever, which is different from most of the diseases I deal with,” the veterinarian from Stratford, Ont., told the Banff Pork Seminar.
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Producers have been knocking back the devastating hog disease with new vaccines for sows and gilts that show better than expected results even before field trials were complete.
Formally known as porcine circovirus type 2, or PCV2, it appears to have little effect on nursery pigs, but hits hogs hard in the finishing barns.
Hog specialist Laura Batista of the veterinary college in Ste. Hyacinthe, Que., said the disease is probably present in all herds in North America and is sometimes confused with other conditions such as porcine reproductive and respiratory syndrome, or PRRS.
Proper diagnosis is important to ensure that the proper medicine is administered.
Batista believes different strains of the disease exist and that severity varies between regions.
She said it is difficult to keep diseases out of modern pigs because of intensive management practices.
“The bigger the pen was, the higher the probability of having the disease and unfortunately, the way we produce pigs today, we rarely ever have down time in the farrowing room and the nursery.”
A sow vaccine has been available in Canada for less than a year. It was distributed among 41 veterinarians and used on 77 farms to treat 55,000 sows. About 65 percent of farms saw a reduction in the disease.
Vaccines have been available in Europe for about two years. Those using the vaccine saw mortalities drop and noticed improved average daily gains and feed efficiency.
Jones said the results were almost too good to be true and there are still many unknowns.
It is not believed that antibodies that are transferred from sows to piglets play a significant role in the vaccine’s effectiveness in animals of different ages.
However, there appear to be fewer problems among older animals, said Robert Desrosiers of the pharmaceutical company Boehringer-Ingelheim that is also offering a vaccine.
Researchers do not know at this point if sows must be vaccinated regularly to keep immunity strong.
Batista and Jones recommend conscientious animal husbandry, as well as administering a vaccination program.
“There are lots of principles of good management that we all know and have known about for years, but we also have a tendency to cheat on,” Jones said.
He recommended a number of management changes:
- Stop cross fostering pigs in the first 24 hours of life because this increases the risk of disease.
- Identify and remove sick animals early from pens and limit pig-to-pig contact.
- All in, all out barn movement should be practiced so disinfection between groups of pigs moved in and out can take place.
- Do not commingle pigs if possible.
- Effectively monitor and diagnosis diseases.
- Make sure pigs have enough space. Clean out feeders and waterers so toxins are not left behind.
- Offer good nutrition that is highly digestible. Consider offering gruel to sick pigs to get them to eat.
- Keep timely, accurate records and link production, health and financial information.
Information is crucial when these diseases strike.
Jones said a lack of co-ordinated information on the disease is a big problem. He wants to see more sharing of information among veterinarians, producers and other industry participants because another new disease could be equally troublesome.
“Certainly within my career there will be another new PCCV agent that will be a new or emerging disease that we will have to deal with,” he said. PCV2 was formerly called postweaning multisystemic wasting syndrome.
Hog veterinarians in Western Canada began reporting cases of nursery pigs falling ill in the early 1990s. They reported a progressive loss of body condition, visibly enlarged lymph nodes, difficulty breathing, diarrhea, pale skin and jaundice. The disease depletes white blood cells critical to immune response.
PCV2 was isolated from these outbreaks in 1997. It only occurs in pigs, is stable in the environment and is resistant to many common disinfectants.
