It’s Time to Unravel How Multiple Swine Pathogens Interact in the Pig

It’s one thing to know how a disease pathogen affects a pig. It’s another thing to know how multiple disease pathogens affect a pig.

“There's a lack of understanding of the interaction between enteric and respiratory pathogens,” Fernando Leite, technical manager for enteric diseases at Boehringer Ingelheim Animal Health, explained during an Industrial Partner Session at the American Association of Swine Veterinarians annual meeting in Nashville. “Multiple pathogens can affect swine, yet there hasn't been a field evaluation of enteric and respiratory pathogen challenges together to better understand their consequences.”

That’s what led Leite and Guilherme Cezar, graduate research assistant at Iowa State University, to conduct the Dynamic Pig Health Project – aimed at understanding swine health and the consequences of pathogen challenges better. 

“We are always thinking about how we can help veterinarians and producers the best we can in the industry. Fundamentally, we realize there's a lack of investigations and understanding of pathogens as a whole, their interactions, affecting swine and swine populations,” Leite says. 

FINDING PRACTICAL ANSWERS IN THE FIELD
Cezar says the beauty of the Dynamic Pig Health Project is that it was conducted in a real-world setting, following the pig around from weaning to market. Along the way, Cezar and his team collected samples of oral fluids from 40,000 pigs. From those samples,12,000 PCRs were performed. 

“We could test for all these pathogens that were specific to porcine reproductive and respiratory syndrome (PRRS) and Lawsonia. Then, we evaluated their interaction in the field, in conditions that are a reality for the producer,” Cezar explains.

All of the pigs in this project were negative for PRRS when they entered the production system. Along the way, the pigs got PRRS. One of the key findings of this project was when they did get PRRS, all the groups that had low average daily gain and higher mortality also had higher detection of Lawsonia in their oral fluids as well. 

This held true for porcine circovirus 2 (PCV2), too. The groups that had a higher incidence of PCV2 compared with the others also had the higher amount of Lawsonia in terms of PCR detection. 

“This is a unique study,” Leite says. “This interaction of Lawsonia with PRRS and PCV2 hasn’t been done before. It also took place in the field, not a lab. I think it's the first time that these interactions have been unraveled.”