With the apparent increasing prevalence of large bowel diarrhea (LBD) in growing pigs over the last five years, complex questions about the cause of the syndrome have reemerged, as have measures for treatment, says James Lowe, DVM, Carthage (IL) Vet Service.

Submissions to state diagnostic laboratories have been on the rise, as have discussions of grow-finish diarrhea at swine veterinary meetings.

For many veterinarians, this old disease is clinically new, as all-in, all-out production practices, multi-site production schemes and improved swine diets have served to reduce the prevalence of LBD to below observable levels, Lowe said in a talk at the Leman Swine Conference in St. Paul, MN, in September.

Historically, cases of LBD were a rare event, except for the occasional case of atypical Lawsonia intracellularis, presented as only a colitis and not ileitis, Lowe says. From 1998 to 2005, his data suggests that clinical LBD was present in less than 5% of the lots observed in all-in, all-out production.

But he has seen a significant increase in the number of diagnostic submissions for LBD in finishing pigs in the last four years (Table 1). Some reasons for increased LBD include better and more rapid tests, sampling bias by veterinarians, and a true increase in disease prevalence. Likely it is a combination of those factors, he says.

Root Cause Uncertain

The root cause of LBD has been varied, with a definitive diagnosis of a single disease agent seemingly impossible to achieve, Lowe says, because single agent models of disease don’t accurately reflect the ecosystem diversity in the large intestine of pigs, Lowe says.

LBD due to swine dysentery has been a rare diagnosis. More commonly, mild colitis and salmonella are equally identified.
More likely, the cause of non-specific LBD in finishing pigs appears to be multifactorial, Lowe reinforces.

Cooperative Approach

The logical approach in managing LBD should be a cooperative effort by the veterinarian, nutritionist and production team. “The veterinarian must make every effort to implement an effective diagnostic plan to rule out swine dysentery due to Brachyspira hyodysenteriae,” Lowe stresses.

The team must take care not to implement interventions that could prove more costly than the disease. Diet changes might reduce the prevalence in groups with LBD or the incidence of LBD within groups, but the cost of the change could easily be higher than the cost of the disease.

The use of antimicrobials, which may appear to provide short-term resolution, needs to be closely monitored for long-term reduction within in-group incidence and known economic benefits of intervention to justify their long-term use, he continues.

Adopt Stringent Cleaning

Lowe says common disease management practices can minimize LBD in finishing pigs.

“Good between-group hygiene appears critical for controlling all forms of enteric disease,” he observes. “As an industry, we often fail to implement adequate cleaning between batches of finishing pigs. This lack of cleaning, coupled with short downtimes between batches that do not allow for adequate drying, lead to an increase in the number of enteric organisms in the barn when pigs are placed. Over time, this shift in environmental contamination can lead to outbreaks of enteric disease.”

Adopting intensive cleaning programs between batches of growing pigs can reduce incidence of all diarrheas for all practical purposes to zero.

“The key to these programs is rigorous third-party inspections for the removal of organic matter and extended dry time (14 days),” Lowe says.