Managing rapidly evolving swine diseases

A porcine respiratory disease is of particular concern because it can rapidly evolve

There are signs that a number of potentially damaging disorders of pigs are either developing immunity to common drug treatments or becoming much more common as a result of well-established protocols, attendees at the recent Shakespeare Swine Seminar were warned by a Minnesota veterinary practitioner.

Why it matters: When treatment for swine diseases are no longer effective, it means more expense and challenge for farmers and industry experts.

A promising innovation for combatting one of these rapidly evolving disease organisms is gene editing, said Dr. Mark Fitzsimmons. But he’s concerned a recent ruling in Europe will one day eliminate gene editing as a globally accepted food sector technology.

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The Fitzsimmons family runs about 10,000 sows in southern Minnesota and as a practitioner with Swine Graphics Enterprises and Protein Sources Management, Fitzsimmons also does private consulting in systems with up to 40,000 sows.

First on his list of diseases for which it appears that control methods may be losing their effectiveness was PRRS (porcine reproductive and respiratory syndrome). Recent experiences with the PRRS virus from the 1-3-4 DNA sequence family indicates that the established protocol of vaccinating gilts continues to be effective. But in barns showing up with the also-common 1-7-4 DNA sequence family, the PRRS virus, “has not followed immunological rules,” Fitzsimmons reported.

“This thing has been a problem,” he said. “With the slightest little change in the genome, it will abort sows that it aborted six months ago.”

Usually once sows are exposed to the disease, they will have some immunity.

As a result, he finds himself advising producers in pretty much the same way he might have done 30 years ago. And it’s making him feel as if “we have just failed miserably, as an industry, as academics, as the veterinary community, to improve this situation for the producers in this room.”

Fitzsimmons sees hope only in gene editing efforts already underway in the United States, to create pigs with no susceptibility to PRRS. But he noted the possible chilling effect of a recent ruling by the European Court of Justice that gene editing — cutting out parts of a DNA sequence to stop the expression of specific traits — should be classified as genetic engineering in the same manner as the older and less-precise technology of inserting DNA from another organism.

Fitzsimmons said influenza has recently shown a similar tendency to evade well-established swine health measures. “We are seeing a different type of flu in terms of the way in presents itself in symptoms,” he said. His theory is overuse of flu vaccines.

And pelvic organ prolapses — predominantly the uterus — are also showing up with much greater frequency than in the past. In this case, he believes the industry needs to look at the issue of hormone levels in gilts and sows under current production systems.

Prolapses increased slightly in the U.S. in 2013 and 2014, he said. More dramatic increases began in November of 2014. Now, there are farms with 20 per cent mortality among sows, and 15 per cent of the mortality is attributable to uteral prolapses. In most farms, prolapses now represent 25 per cent of all mortalities among sows.

Fitzsimmons showed slides of sows that were 10 or 15 days away from farrowing, but could have been confused for sows set to farrow that day. Then he showed slides of a uterus from a deceased 20-pound gilt, and it was much larger than what would have been observed in the past.

“We’re not finding anything that would give us any indication of mycotoxins,” he said. And that has led him to the conclusion that what appears to be a troubling trend in swine genetics “is hormonal in nature.”

Fitzsimmons gave both pre-meal and post-meal presentations at the 2018 Shakespeare Swine Seminar, covering a range of topics including managing lactation feed intake, automated feed systems, and fostering piglets in “nurse litters.”

About the author

Contributor

Stew Slater operates a small dairy farm on 150 acres near St. Marys, Ont., and has been writing about rural and agricultural issues since 1999.

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