Summer is the peak season for Lawsonia intracellularis, the bacterial pathogen causing ileitis. Diarrhea and reduced growth rate and feed utilization, which lead to increased market weight variation, are hallmarks of the disease. However, according to Dr. Brett O’Brien, swine technical services veterinarian for Merck Animal Health, an ileitis infection may be hiding in your herd.

“In subclinical ileitis, diarrhea is absent. But significant thickening of the ileum and adjacent intestinal tissues hinders the pig’s ability to fully absorb energy and nutrients from its feed,” Dr. O’Brien explains. A study showed subclinical ileitis had a 20.4% negative impact on feed efficiency over 6 weeks post-challenge.¹

Nate Winkelman, DVM, has reported that in controlled challenge studies of pigs 10 weeks of age or older (the typical age of pigs infected in the field) with high challenge loads, the majority of the pigs will exhibit the subclinical form of ileitis. Pigs can shed Lawsonia for up to 10 weeks post-exposure, increasing potential spread.² A study calculated the performance loss from subclinical ileitis at $3.50 to $5 per pig³.

“Diagnostic monitoring of fecal samples and PCR testing can help identify subclinical ileitis within a pig population,” says Dr. O’Brien.

She emphasizes that producers can control Lawsonia through proper barn sanitation and reducing stress on swine herds can help control Lawsonia.

“In the peak of summer, stress can be the catalyst that breaks a subclinical disease into a clinical one,” Dr. O’Brien notes. “Clinical cases of ileitis typically begin after marketing starts because pigs incur the additional stress of reestablishing their social hierarchy within pens where pigs have been removed.” She recommends minimizing environmental stressors like overcrowding, feed outages, additional disease challenges and ventilation problems. An efficient vaccination protocol can also help, she says.

“We’re always looking for what I call the Holy Grail – how can we put more antigens in one bottle and minimize injections?” Dr. O’Brien adds, “That’s the benefit of a product like CIRCUMVENT^Ⓡ CML, which vaccinates against PCV 2a and 2d and Mycoplasma hyopneumoniae in addition to Lawsonia. You have one bottle, ready to use, reducing stress and lessening the chance for administration errors.”

Dr. O’Brien also recommends compliance monitoring to alert producers to a problem with their vaccine protocol, including a missed vaccine, timing issues or disease present at the time of vaccination, which may hinder the appropriate immune response elicited by vaccination.  

“Having a vaccine that’s immune response can be monitored serologically post-vaccination allows veterinarians and producers to maximize the complete value of their ileitis vaccination program,” she says. “It is important to make every injection count.”

Dr. O’Brien says vaccine choice can play a role in effective compliance monitoring.

“Merck Animal Health supports diagnostics so folks can understand their Lawsonia status in different flows of pigs within their production systems,” she concludes. “Compliance monitoring has proven to be a huge value for producers and veterinarians working to help ensure success.”

To learn more about Merck’s swine health product and vaccine portfolio visit www.drivenbyprevention.com or contact your local Merck representative.

_References:

¹_{Paradis MA, McKay RI, Wilson JB, Vessie GH, Winkelman NL, Gebhart CJ, Dick CP. Subclinical ileitis produced by sequential dilutions of Lawsonia intracellularis in a mucosal homogenate challenge model. American Association of Swine Veterinarians. 2005; 189-191.}

² _{Guedes R. Update on epidemiology and diagnosis of porcine proliferative enteropathy. J Swine Health Prod. 2004;12(3):134-138.}

³_{Winkelman N. Subclinical ileitis: Diagnostic monitoring, R}²_{, and economics. March 2018. Proceedings of the 49th Annual Meeting of the American Association of Swine Veterinarians. 2018.}