With 11 swine veterinarians on staff, the Swine Vet Center at St. Peter, MN, has the luxury of allowing its veterinary team to specialize.

For Paul Yeske, DVM, that focus was actually developed early on in his career when he realized his strong interest in research, specifically disease eradication. Since he began practicing in 1985, Yeske has diligently researched what others have done and then mapped out and implemented disease elimination schemes for a variety of swine diseases.

“I started out very early in practice doing a lot of mange eradications. Ivermectin (Merck Animal Health) had just become available, and we had the ability to use it to eliminate mange. No one enjoyed spraying pigs and treating pigs for mange,” he says. “It wasn’t a fun job, so that was one of the first things I did in eradication.”

Some of the first disease eradication projects involved using depopulation and repopulation because many of the herds had more than one agent to eliminate and there were no other methods of eradication.

That followed with a joint project with the Upjohn Co. and James Bradford, DVM, to work on swine dysentery eradication. “There were a lot of swine dysentery-infected herds at that time in the late 1980s. We needed to eradicate the disease because it was very expensive due to the ongoing cost to the grow-finish side — the cost of medication or the cost of the disease if you didn’t medicate — so we did a lot of depopulations/repopulations to eradicate swine dysentery in the late 1980s and early 1990s,” Yeske recalls.

Projects in the late 1980s eliminated Transmissible gastroenteritis in sow herds, helped by the move to multi-site production systems. That move and medication also aided removal of atrophic rhinitis.

In the early 1990s, medicated early weaning was used to eliminate Actinobacillus pleuropneumonia from most herds. The National Pork Board also set up a national study to evaluate medicated early weaning and its impact on pigs in the nursery and finishing phases. Out of these studies, Yeske continued to work with clients and other producers on implementing this technology into their herds.

Push on PRRS

“Pseudorabies (PRV) was very prevalent in the swine industry when I started practice and while I served on the National Pork Board’s PRV committee for 25 years,” Yeske says. He was very involved in local, state and national PRV eradication efforts.

With that model, Yeske delved into research on ways to eliminate porcine reproductive and respiratory syndrome (PRRS). “We were following up what some other people had done; we had tried herd closure projects in chronic TGE cases and we decided to use the same herd closure concept to work with PRRS,” Yeske says.

Based on data from Rodney “Butch” Baker, DVM, 200 days was the minimum timeframe for herd closure for PRRS, because his research showed that animals would shed virus up to that period of time. Yeske extended that time period to 210 to 240 days and started having a lot of success with PRRS eliminations.

“As we were doing these PRRS herd closures, the question was, ‘can we do mycoplasma at the same time?’” he says. What followed was a number of herd closures out beyond 240 days (proven time of shedding of mycoplasma based on University of Minnesota research), plus medicating sows and pigs at the end of the time period. “We were able to get mycoplasma out of a lot of herds, and many have stayed negative for mycoplasma.” PRRS virus was also eliminated, although Yeske admits that some herds have become reinfected with a different strain of the virus.

Yeske has completed numerous research trials on PRRS that have continued to provide him enjoyment and educational rewards. They include:

•       Tail swab testing for PRRS virus in piglets. This study verified that this can be an easier way to test piglets following a routine procedure of tail docking and is comparable to blood samples. Swabs from ear notches were also successful.

•       A survey of finishing sites to determine how many negative pigs placed in pig-dense areas become infected. In the study, an average of 46% of the negative pigs turned positive.

•       Thirty-nine herds that were either depopulated/repopulated or were startup operations were followed for eight years to determine the survival rate for staying free of PRRS. Herds were assessed for biosecurity scores using the Production Animal Disease Risk Assessment Program (PADRAP) developed by Boehringer Ingelheim Vetmedica, Inc (BIVI). External risk scores were very predictive of herds that would break and were more likely to break down at a faster pace than herds that had a lower PADRAP risk score. Location was the number one factor for external risk of breaking with PRRS.

•       A PRRS vaccine study recently completed and reported at the March annual meeting of the American Association of Swine Veterinarians (AASV) in Denver determined that PRRS modified-live virus vaccine (BIVI) did not represent a major threat to regional spread of PRRS virus. “This study follows the earlier study that says nearly half of negative pigs are becoming PRRS-positive when they move into pig-dense areas, and what can we do to help prevent this from happening. From vaccine research at Iowa State University, we found that the PRRS vaccine helps in controlling the disease in the grow-finish phase, but is its use a risk to sensitive farms?” Yeske questions.

Findings in this BIVI-funded, 30-day project determined that vaccine virus was found only 2% of the time at a mile’s distance, only 6% of the time in the barn, and 6% of the time right outside the pit fan. The test was done in March at a time when the system was using minimum ventilation, a prime time for spread of the PRRS virus, he says. “I think everyone was expecting the virus to move, but we thought the bigger surprise was that the virus was only detected for 14 days. We found virus spread can happen, but it is a pretty low-frequency event. The most surprising piece out of the study was that this research was conducted in two, side-by-side rooms and the room with the negative, unvaccinated pigs stayed negative throughout the entire finishing phase. Air space was separate, but the door separating the two rooms was just 6 in. away.” 

Antibiotics Research

Yeske has participated in research on several new animal drug applications for approval of antibiotics by the Food and Drug Administration. Producers have changed animal production flows, switched to multi-site systems including all-in, all-out by site, and formulated proactive vaccination schedules. But they still need antibiotics in their animal health arsenal, he says.

“We need antibiotics in two roles — to treat animals and to prevent disease. Going forward, if we as veterinarians know the farm, know the flow of pigs and history of risk, then we can be proactive rather than reactive. And I think if consumers really understood that, they would want us to be proactive,” he emphasizes.

Producers support the proactive approach for two reasons — they don’t like sick pigs and it lessens the cost.

Producer Research Barns

Yeske and Tim Loula, DVM, partner at the Swine Vet Center, and one of Yeske’s chief mentors who helped him become a better veterinarian, spend the most time coordinating research at the four nearby research farms. Each is operated on behalf of an individual producer. All are 2,500-head, wean-to-finish units. The barns fill a void caused by the reduction in university-funded research.

“Particularly, when we built the first two research barns in 2006, we realized that the decisions are bigger and each decision you make needs to be right, so you have to have quality research to complete the decision process,” Yeske states. “We were fortunate in that Mike Brumm (Brumm Swine Consultancy, Inc.) was retiring from the University of Nebraska and moving to Mankato (MN). He helped set up the barns. He is director of research and consults with us on field-applied research.”

Research barns are built as close as possible to commercial conditions in each of the producer’s barns, with the goal of helping them with management decisions they face back at home. Meeting with clinic team members and producers to draw up research protocols for trials at the barns is a continuing source of enjoyment for Yeske.

Swine Diagnostics

Yeske, the AASV’s 1998 Swine Practitioner of the Year, sees value in research supported by improved diagnostics and is excited about the role of oral fluids.

“Cotton ropes allow us to sample more animals and do better sampling on site. In the future with this technology, we may have field-side tests that tell us if disease agents are present, which could guide us in making decisions on when to intervene with treatment,” he observes.

Oral fluids have the potential to help the industry learn a lot more about disease dynamics, early diagnosis and quicker intervention. The technology is being used in the research barns as a way to monitor status for PRRS, swine influenza virus and Mycoplasma pneumonia.

Later it may be used by pork producers to monitor antibiotic use and residues in late finishing as a way to preserve pork exports, Yeske foresees. 

Success Brings Happiness

Yeske says the most satisfying part of his job is working with the pigs and sharing in the happiness of farm workers who are successful in production.

“We sit down with each of our sow farms that I work with and do production goals at the beginning and end of the year. I’ve told them that I will buy them pizza for lunch if they achieve their goals. So the best thing that can happen is I buy them pizza every quarter and everybody is happy. For me, that is the fun part about practice — seeing the farms perform and doing what we think they can do,” he says.

Career Motivation

Yeske grew up on a small cattle and pig operation at Villasca, IA. He advanced his enjoyment of pigs while expanding his finances and hog experience by working at a neighbor’s 300-sow, farrow-to-finish operation all through high school. “I wanted some more experience and I wanted some more cash,” Yeske says with a chuckle.

His interest in swine veterinary medicine grew from interaction with local veterinarian Ray Denham from Cumberland, IA, who consulted for the family farm. Yeske spent a couple of summers working with the veterinarian gaining experience and mentoring while pursuing his veterinary degree on Iowa State University. He also worked part-time while in college on farms around Ames, IA, to gain practical pig experience and generate income.

Following college graduation in 1985, he joined Loula at the Nicollet-New Ulm (MN) veterinary clinic doing dairy and swine work. In 1990, the pair decided to specialize in pig veterinary care by starting the Swine Vet Center.

Yeske received his master’s degree in 1998, studying personality profiles of swine farm managers. He also completed the Executive Veterinary Program at the University of Illinois in 2009 on personality profiles of producers.

Lessons on Sows

During his high school and college years, all of the farms that Yeske worked on had sows in pen gestation. “Pen gestation wasn’t friendly to the people or the animals. Sows can be managed in pens and they can work, but individual housing in gestation gives us the opportunity to really meet the needs of the animal.

“We can properly feed them, we can easily visualize each of the individual animals, and we can provide a much better environment,” he adds.

European production systems he visited have clearly shown that in housing systems where sows had a choice, they chose to spend most of their time in stalls rather than in group pens and in an aggressive situation with another sow.

“Producers moved sows inside and away from the elements, and then in confinement from pens to stalls, because it was good for the animal, not because of economics. The economics followed, but they did it because it was better for the animals,” he stresses.

If group housing wins out, it will increase production costs, cut farm productivity, reduce availability of pork and, most likely, will raise the price at retail, Yeske warns.

Education is still the key to “making people understand why we’ve made those changes and how it all factors into producing a safe product that is economical and has great flavor. It’s the industry’s job at the grassroots level to tell the good message about pork,” he concludes.