At times, it seems that the swine industry is riddled with disease and that certain diseases are nearly insurmountable to treat and control.
Mention swine diseases and the first thing that comes to mind for most producers and swine veterinarians is porcine reproductive and respiratory syndrome (PRRS). PRRS has been a very frustrating (and expensive) disease, and it continues to plague our industry in many ways today.
While PRRS has been virtually a constant nemesis, the industry has really made great strides over the last couple of decades in controlling other serious disease pathogens. Hog cholera has been eradicated, and we appear to be on the doorstep of pseudorabies eradication as well. Almost forgotten are diseases like atrophic rhinitis, mastitis-metritis-agalactia and other common maladies.
External parasites such as lice and mange have met their match with the new ivermectins, such as Ivomec and Dectomax. These products and others like them have worked so well that many farms were able to completely eradicate these problems.
In fact, should I come across hog lice these days by chance, it is such a novelty that I usually feel compelled to exclaim: “Wow! Look at this!”
As the battle with PRRS continues to rage, we need to occasionally look back at some of the strides we have made in our war on swine diseases.
Recently, Robert Desrosiers, DVM, Quebec, Canada, presented the Howard Dunne Memorial Lecture during the 35th annual meeting of the American Association of Swine Veterinarians.
Desrosiers' lecture, entitled “Epidemiology, Diagnosis and Control of Swine Diseases,” outlined the progress that has been made, and some of the sweeping changes in our knowledge of swine diseases. Below are some of the highlights from that lecture.
First, Desrosiers presented in detail what science has taught us on epidemiology of swine diseases, because as he put it, “to avoid losses associated with significant pathogens, we need to know by what means they find their way into swine barns.”
Desrosiers said that direct, pig-to-pig contact has actually been overrated when it comes to transmission of swine disease, and that the aerosol mode of spread has often been overlooked as the primary cause. To support his argument, Desrosiers cited over 100 scientific papers implicating aerosol as the primary suspect in disease transmission.
At the same time, he doesn't discount other means of transmission of disease (especially PRRS virus) that have been demonstrated recently, such as insects, people and vehicles, and cautions us not to ignore these other indirect means of transmission. In just the last decade, we have come a long way toward understanding how diseases spread.
Next, Desrosiers dealt with the issue of diagnostics. He stated: “Efficient control of health problems starts with knowing what we're dealing with.”
We have been the recipients of huge strides in science with diagnostic testing, which makes our jobs easier and allows us to practice with a much greater degree of certainty when dealing with disease problems. With tests such as Polymerase Chain Reaction (PCR), molecular genetics such as sequencing of viruses, the vast array of Enzyme-Linked Immunosorbent Assay (ELISA) and dozens and dozens of new technologies, we have come to expect the diagnostic laboratory to perform miracles.
Desrosiers reminded us that while these new tests are amazing, and have given us tremendous power to determine the cause of a given disease, none of these tests is perfect, nor should this technology ever replace our God-given skills and common sense. It is often the power of keen observation and the art of practice that ultimately gives us the answers to a difficult problem.
Lastly, Desrosiers addressed the issue of control, prevention and treatment of swine disease: “Now that we know what we're dealing with and, hopefully, how it got into the barn, what do we do with it?”
In discussing various control and treatment strategies, he used examples of how new vaccine technology and health technologies such as multi-site production, segregated early weaning and new antibiotics have resulted in significant advances, even with some diseases that looked unbeatable a few years ago. These tools have helped us eliminate a number of swine diseases that once threatened our pigs and our livelihoods. Desrosiers challenged veterinarians to use these tools wisely and judiciously, or risk the loss of access and effectiveness.
Finally, Desrosiers challenged swine veterinarians to continue to meet and exceed expectations, especially those related to “bugs and diseases.”