Ileitis caused by Lawsonia intracellularis has been a frustrating problem for pork producers for many years.

Although several antimicrobials have been shown to control the clinical disease, outbreaks among growing pigs and replacement gilts have been, in some instances, devastating.

The acute form of ileitis is sometimes dramatic, giving rise to blood-tinged diarrhea and occasionally sudden death. This form of the disease is especially maddening when the affected animals are bred gilts about ready to farrow.

A more insidious manifestation of the disease is the subclinical form that robs profits by lowering performance. Many times, this form of the disease goes unnoticed unless individual pigs become chronically infected. These pigs never achieve market weight, and if they do not die, are often considered of no value at close out.

A novel approach to controlling ileitis has been the introduction of an avirulent (nonpathogenic) live vaccine. It has had a huge impact on both the incidence and severity of ileitis outbreaks, and has reduced the reliance on antimicrobials in replacement gilts and grow-finish.

The following case studies demonstrate how antimicrobials and the avirulent vaccine can reduce disease and improve performance.

As with any new technology, there is a learning curve with this vaccine. The second case study outlines the attention to detail needed for proper immunization.

Case Study No. 1

A farm purchasing replacement gilts was concerned about preventing ileitis in new animal introductions. Females had a history of late grow-finish death loss after entering into the replacement sow farm. Medication would reduce, but not completely eliminate, clinical signs of ileitis. To prevent losses associated with ileitis, replacement females were vaccinated prior to leaving the grow-finish farm.

The vaccination protocol at the source farm was performed exclusive of any feed medications shown to be effective against ileitis. The vaccine label requires no antibiotics for three days prior and three days after vaccination.The producer gave developing gilts a full dose of vaccine after hearing about reduced efficacy and clinical signs from neighbors who had tried using a partial dose of the vaccine.

A pulse dose of therapeutic levels of chlortetracycline (10 mg./lb. body weight) was implemented to protect animals during the process of developing active immunity, about four weeks after vaccination.

Gilt performance in the grow-out barn reflected a 35% reduction in mortality, 8% improvement in growth rate and reduced medication use. Gilts were able to enter sow farms without any losses. No feed medications against ileitis were needed.

Case Study No. 2

A grow-finish system was experiencing finisher losses due to ileitis. Pigs throughout finishing would develop runny stools and grow poorly. Heavyweight animals just before and after first marketings from the barns would develop black stools, or simply be found dead with bloody feces. Feed medication with tylosin at 100 and 40 g./ton reduced clinical signs, but did not prevent outbreaks.

The finishing manager decided to try vaccination with the water-soluble ileitis vaccine from Boehringer Ingelheim (Enterisol Ileitis). Grow-finish pigs in 11 barns were vaccinated, and 10 comparable barns were left as controls.

All feed medications were taken out of the last nursery diet to allow vaccination without inactivating the live vaccine. A Ready Pack container with dye and chlorine neutralizer was used to prevent inactivation of the vaccine by any chlorine in the water. The producer charged the lines to all the pens that were getting vaccinated.

Feed medications were removed during the last 10 weeks of production in vaccinated barns to fully check vaccine potential. A growth promotant such as 10 g. of tylosin or BMD was used in the first 10 weeks. Control barns had 100 g. of tylosin in early finishing for three weeks, and 40 g. of tylosin in the last two diets.

No breaks of ileitis occurred in the vaccinated pigs, while several barns of control pigs broke while on medication. Mortality was prevented using tiamulin (Denagard Liquid Concentrate) in the drinking water.

Growth rate was also 5% better in the vaccinated groups. Reducing the level of medications paid for over half the vaccine cost.

Conclusion

The use of this new technology requires careful planning on the part of the producer and their veterinarian. Timing of the vaccination is critical since it requires at least three weeks for the pigs to acquire immunity. Using vaccine with approved medications can allow producers to prevent and control ileitis, while at the same time reducing their reliance on continuous feeding of antibiotics.