Postweaning diarrhea is a syndrome with many causes, but most cases are due to K88 and F18 strains of Escherichia coli.

A 200-sow, farrow-to-finish, single-site farm produced pigs in batches. Due to space/time restrictions and marketing opportunities, the farm changed from a 10-group system (batch every 14 days) to an eight-group system (batch every 18-19 days).

With the system change, wean age and wean weight were significantly increased. Instead of weaning pigs at 13-19 days of age at 8-12 lb., pigs were weaned at 19-26 days of age at 14-20 lb.

In spite of these changes, the producer and feed supplier were reluctant to change the feeding program.

However, after the third consecutive batch of pigs broke with severe scours after weaning, the producer was ready to make changes.

He tried numerous water and injectable medications with virtually no response. Most of the weaned pigs became ill, and death loss exceeded 10% in one group.

Tissues from several recently weaned, untreated pigs with diarrhea were submitted for lab testing. Pure hemolytic E. coli (untypable) was cultured. The organism was resistant to all suggested antibiotics.

Citric acid was added to the water, diet changes were made to accommodate the size and age of weaned pigs and pigs were fed multiple times a day. Zinc oxide was added to the feed at 3,000 ppm.

These steps, plus removal of feed-grade antibiotics, brought much improvement. Except for a few sick pigs, this farm has been free of major breaks for over six months.

Case Study No. 2

A 2,400-sow herd with three-site production weans 17-21-day-old pigs twice a week. Each nursery room receives one week's worth of pigs, and each nursery site has a four-room building that receives four weeks of pigs.

Several miles separate the three production sites. Each site has its own water and washing equipment, but the same staff manages all three sites.

Site A experienced severe diarrhea in weaned pigs. All four rooms were affected at 5-10 days after arrival from the sow farm. The sow farm had not experienced any unusual clinical diarrhea.

The owner had gotten very poor response using several different water medications. Pigs were dying very soon after the onset of diarrhea, and nearly the whole group was affected within a few days.

A thorough examination of the site, procedures and personnel was conducted. Pigs with acute diarrhea were slaughtered and tissues were submitted for lab testing. Results were positive for an F18 hemolytic E. coli.

During the site exam, it was discovered that several incidents had occurred on the previous “turn” of the site. A commercial hauler had used a dirty truck to transport pigs from the nursery to the finisher. Staff was shorthanded on load-out day and didn't change clothes after loading pigs. The power washer heating element was not working, and some rooms were washed with cold water and no disinfectant before they were reloaded with weaned pigs. Fortunately, the personnel did change clothes and boots routinely as they went between sites.

After the biosecurity lapses were uncovered, personnel were retrained. The concern is that the F18 organism is not easily destroyed, and can be tracked around within a system.

To prevent site and between-site contamination, farm staff was required to validate procedures. Personnel were given full responsibility and authority to act on situations that were not in compliance with accepted procedures.

The affected site was the only one that showed signs in this system, and was intensely cleaned and disinfected on the next turn. Pigs were injected with an F18 E. coli vaccine for two turns. Efforts were made to use water acidification and reduce stress factors that trigger diarrhea outbreaks. E. coli problems were minimized.


Biosecurity and sanitation are keys to controlling risk factors.

Newly weaned pigs should be kept comfortably warm and dry, especially in the first few weeks.

Feed access and formulation should be precisely managed to meet the nutritional needs of the pigs.

Most pigs produced today are raised in very clean environments and may not acquire “normal” intestinal organisms to develop the flora in the gut, which may reduce clinical disease. Vaccination of newly weaned pigs with non-toxigenic K88 or F18 strains of E. coli gives variable results, but may help to reduce the clinical signs of postweaning diarrhea.

There are now several genetic lines of pigs that have E. coli resistance.

Prevention and control of postweaning diarrhea requires good records, good communication, intense and persistent effort and routine diagnostics.

Be sure to include your veterinarian when experiencing production or health challenges.