“Porcine respiratory disease complex (PRDC) remains one of the main challenges for the U.S. swine industry, impacting both performance and profitability,” says Dr. Eduardo Fano, DVM, Technical Manager for Mycoplasma, Boehringer, Ingelheim Vetmedica, Inc. “PRDC includes both viral and bacterial respiratory pathogens, specifically Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), Porcine Circovirus type 2 (PCV-2), Influenza Type A Virus-Swine (IAV-S), M. hyopneumoniae (M.hyo) and secondary bacterial agents. Clinical manifestation of PRDC and respiratory pathogen interaction are dependent upon the production system, environmental conditions and infection level of the different pathogens present in the population.”
Because PRDC can involve several disease agents and has a wide range of clinical presentations, Dr. Fano says proper diagnosis of disease/syndrome is necessary to accurately identify the pathogens involved.
“Improper diagnosis could delay appropriate intervention and have a negative effect on the development of an effective PRDC management strategy,” he says. “Consequently, incorrect management of PRDC could negatively impact production and profitability of the farm. Identifying PRDC agent presence via serology or oral fluid testing is useful. However, individual-based diagnostic testing focused on identification of the causative agent of the clinical event is necessary to indicate whether the PRDC management strategy is working properly. Tissue diagnosis from appropriate pigs allows the practitioner to identify both the disease agent and lesions which leads to a clear understanding of pathogen participation.”
The Coughing Pig Project is a diagnostic initiative that can aid producers in timely PRDC management decision making. Dr. Fano explains that the protocol for the project involves selection of a minimum of three pigs (exhibiting clinical signs; no other ailment; not treated) and collection of a full set of tissues. These tissues are submitted to a diagnostic laboratory for screening on histopathology, immunohistochemistry, PCR, and bacterial culture. In these projects, pig groups were considered diseased when one or more pigs tested positive for both pathology and antigen presence. To date, twenty-two projects have been completed and the results indicate that, despite clinical signs thought to be due to M.hyo, only 30 percent (7/22) of the projects were associated with a M.hyo infection and M.hyo infection was always involved with a co-infection of another disease agent:
- 2/7 projects were associated with IAV-S
- 3/7 projects were associated with PRRSV
- 6/7 projects were associated with secondary bacteria
Infections of Influenza Type A virus (8/22 projects), Porcine Reproductive and Respiratory Syndrome virus (11/22 projects) or secondary bacterial infections (14/22 projects) appeared to be more prevalent.
“As a result of these projects, participating farms and systems are able to utilize the diagnostic information to both perform timely and appropriate disease intervention and to aid in understanding the Infection Chain™ for all PRDC pathogens present in the system,” says Dr. Fano. “Understanding PRDC pathogen participation can allow producers and veterinarians to implement customized PRDC management strategies that can minimize the impact of PRDC on performance and profitability in their herds.”
For more information on the Coughing Pig Project Initiative, watch this short video interview with Dr. Fano.