Swine edema is not a widespread problem, but when it strikes it can wreak havoc on nursery pigs.

The disease tends to appear in the nursery 10 to 21 days after weaning, says Brad Bosworth, a veterinarian at the National Animal Disease Center in Ames, Iowa. Bosworth has been working with Harley Moon, an Iowa State University veterinary pathologist, on the edema disorder.

In the worst cases, it causes 30 percent to 40 percent nursery death loss. A strain of E. coli causes the illness by colonizing in the pig’s gut.

But this is not the E. coli.0157 strain that can lead to human health problems. “To our knowledge, this strain has never been associated with illness in humans,” Bosworth says.

The strain appears selective as to when it will strike pigs. “Before weaning, piglets seem to pass the pathogen through the gut,” he says. “It doesn’t attach well to the gut. But sometimes in the nursery, it does stick, colonize and produce toxins.”

Those toxins cause diarrhea. The disease may move rapidly through a pen of pigs. Death can occur in two days. In clinical trials, even when death doesn’t occur, swine edema can severely curtail weight gain. In less severe cases, you may see diarrhea and only 1 percent or 2 percent mortality.

Weaning age seems to be irrelevant. Pigs weaned at 15 days break 10 to 21 days after moving to the nursery. The same is true for 21-day-old weaned pigs.

If you suspect swine edema in your herd, call your veterinarian to have samples from your herd sent to a diagnostic lab. At least have post-mortem exams done.

Jim Samuels, assistant professor at the College of Medicine at Texas A&M University, is developing a vaccine. It’s a toxoid made from a variant of the E. coli pathogen.

Samuels says in theory you could vaccinate sows or pigs in the farrowing house before moving them into the nursery. Still experimental, the vaccine is not yet approved for use. However, early tests show it to be effective in relieving even the growth lag from swine edema.