Mystery hog disease to become common on Prairies: vet

SASKATOON – Veterinarians have pulled the mask off a mysterious pig disease, and they say pork producers should get used to the face of PRRS.

Porcine Reproductive Respiratory Syndrome will almost certainly become endemic in Western Canada, said Camrose, Alta. veterinarian Frank Marshall to producers at the March Prairie Swine Centre conference.

“It’s here,” he said. “There’s no doubt of that.”

All but one of the major swine breeders in Alberta have PRRS, and many commercial herds have been diagnosed with the disease. Sask-atchewan is about two years behind, Marshall said.

The name PRRS was only given to the disease last summer. Before that it had a variety of monikers, such as mystery swine disease, pig AIDS, blue abortion and swine infertility respiratory syndrome.

That’s because the disease was defined by a variety of illnesses that develop in pigs, and not from one easily identified effect.

“It takes out your first line of defence, so if you have some secondary agents hiding it just allows them to flourish,” Marshall said.

The disease quickly mutates and several varieties have developed. Marshall said even though PRRS is better analyzed now, serum tests from as far back as 1979 show it existed but hadn’t yet mutated into a virulent form.

Hard to detect

The disease has also been hard to spot due to the low rate of clinical outbreaks. Even though many herds have it, only about one in 15 develop clinical signs that ring alarm bells, Marshall said.

If a producer has PRRS, he should know about it.

“If you are a commercial herd and you’re negative, stay so as long as you possibly can,” Marshall said. “If you are positive, make sure you match your incoming animals with your health status.”

Many Alberta producers are only now finding out they have the disease, Marshall said, because herd testing is becoming more accurate. Since PRRS often skulks in a small part of the herd, testing must be rigorous and include many animals to be accurate.

Saskatchewan producers may be able to hold off PRRS longer, Marshall said, because of greater distances between pig operations.

“There are pockets within different areas that still remain negative and will do so for some time. We have the luxury out here of being few and far between in some parts of our pig production systems.”

University of Saskatche-wan veterinarian Chuck Rhodes said many of his clients know about the disease and are working to keep it from their doors.

“We haven’t seen a lot (of infections) yet, but that may change,” he said.

Marshall added many areas will probably have to learn to live with the disease.

“Where it’s real dense, big production areas, we’re going to see it flourish there, and those producers will be positive.”

The growing knowledge on PRRS was obvious from the presentation Marshall gave producers but he said there is still much to discover.

“When we don’t have all the answers, it’s back to basics. Go back to what you really know about management and disease,” he said.

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