Porcine respiratory disease complex (PRDC) is a never-ending challenge for today's pork producer. While advances in production systems are helping in the battle against respiratory disease, the realities of raising pigs in close proximity means strategic programs must be in place to truly win the war.

"PRDC is still a big concern, and will continue to be a focus due to the number of pigs we have in intense production," says Max Rodibaugh, DVM, Swine Health Service, Frankfort, IN. "Respiratory agents are able tohang around, and while herds are healthier as a whole, there will always be carrier pigs which means there will be disease."

So what is the best way to wage war on respiratory pathogens?

Rodibaugh suggests a targeted approach. "In today's economy, producers can't afford anything that is excessive, so we are looking very closely at everything.

"For example, with commonly used Mycoplasmal pneumonia and swine influenza virus (SIV) vaccines, we scrutinize if, where and when to use them. We are also looking to see if vaccination in the sow herd is a better choice to bolster immunity and reduce shedding of organisms to the young pigs. On the antibiotic side, we are identifying the organism that is present so we use the right tools at the right time," Rodibaugh says.

On-Farm Results Mark Townsend, a pork producer in Hartford City, IN, and a client of Rodibaugh's, put this targeted approach to work on his 2,400-sow operation.

"Several years ago, we had a terrible problem with respiratory disease; it became mentally and physically draining to go out to the barn and find more dead pigs. We even depopulated twice, only to 'buy' Actinobacillus pleuropneumonia back in the breeding stock," says Townsend.

Townsend and Rodibaugh worked together to identify the PRDC culprits. "Going to three sites was helping but wasn't a cure-all," Rodibaugh notes.

Postmortem examination identified a typical PRDC mix - SIV, porcine reproductive and respiratory syndrome (PRRS), Pasteurella multocida and Mycoplasmal pneumonia. The next challenge was determining when interactions were occurring.

"We did cross-sectional serology, meaning we bled two different age groups of pigs on the same day. One group, about seven weeks old, were negative to PRRS and the older pigs, at 11 weeks, were positive. This told us the window of when the pigs were seroconverting, so we could intervene," says Rodibaugh.

They also looked at mycoplasma in these pigs and found that only 10% of the 7-week-old pigs were positive for the organism. Yet mycoplasma was present in 70% of the older group.

With the problems identified, solutions could be sought: adjusting gilt acclimation and sow vaccination for PRRS and mycoplasma problems, and using Pulmotil (Elanco Animal Health) at 181 grams/ton in the nursery.

"We cleaned up a lot of our dramatic problems with the new facility, but still had a respiratory situation where the nursery pigs would develop a cough at about two weeks into the nursery (4-5 weeks of age) and stall out," Townsend recalls. "We were looking for a medication that would fit with our system and be effective against the pasteurella and other PRDC pathogens we knew were in the mix."

Nursery Feeding The pigs enter the nursery from 11 to 16 days of age, with their first pellets including Tylan Sulfa at 100 grams/ton. After seven days on pellets, the pigs move to their first grind and mix feed, which includes Pulmotil at 181 grams/ton for 21 days, at a cost of 48 cents/pig. They finish in the nursery with 100 grams/ton of tetracycline.

"We've gotten the mortality rate down from 4% to as low as 1%, and it now stays under about 1.5%," Townsend reports. "But my bigger concern was stunting, which has been solved."

Prior to this program, pigs would stall out and get behind the growth curve. "We needed to get pigs out of the nursery in a better position to grow; I can visually tell they make the transition much better now," he says.

Scrutinizing Payback Rodibaugh notes his clients are judging programs critically and only keeping those providing a return on investment. "When we have pigs on Pulmotil, you can clinically tell it makes a difference. Mark won't give up Pulmotil even in today's economy because the product is making a difference in disease control," the veterinarian says.

While it is hard to pinpoint an exact return, Rodibaugh says most of his clients must get at least a 2:1 payback. "Nothing is guaranteed, but if a producer can predict with some certainty that a product will work, they can lower risk and improve returns," he notes.

According to Rodibaugh, Pulmotil has several unique features that make it a good choice for PRDC control.

The product's mode of action is very targeted toward respiratory disease control, and works in concert with the pig's immune system (see "Tilmicosin Mode Of Action Key To Efficacy").

It is a new, therapeutic, feedgrade antibiotic with a variable dose clearance.

The fact that tilmicosin, the active ingredient in Pulmotil, is not used in human medicine is a benefit in the eyes of the Food and Drug Administration (FDA).

In-feed medication is also favorable to other more time-intensive methods of treating pigs. "We can limit the number of shots we have to give, and don't see a lag in the pigs. The nursery is a critical juncture in the life of the pigs, so you must get them off and going well," Townsend says.

Kenny Brinker of Brinker Farms Inc. just east of Columbia, MO, agrees that programs requiring less labor are more effective. "If you have to go with water solubles or injections, employees are more apt to put it off until they absolutely have to because of the hassle.

"For example, if a group of pigs look a little questionable on Friday afternoon, nobody wants to take the time to mess with it. The weekend crew is smaller, and if they don't get to it by Monday you have a full-blown problem. With an effective product in the feed, you know the pigs are getting treated without extra effort."

Brinker, who runs a 1,200-sow herd, also believes in identifying what is behind the respiratory problem and going after it with the right tool. "We did tissue samples and blood work to find mycoplasma and Haemophilus parasuis," Brinker says. Pasteurella is typically always in the mix as well.

"You have to know what you are up against, and figure where in the system to beat the disease," he explains. "We know that the nursery is where we are going to have PRDC problems, so we anticipate the break and get the Pulmotil in the first feed at 181 grams/ton for 21 days." At $52/ton of mixed feed, the product needs to perform, he says.

Brinker feels it does. "We tried to swim through that three-week period without doing any medicating and noticed pigs were coming out of the nursery 5-10 lb. lighter. That can make a dramatic difference in the finisher, because the bigger they are coming out of the nursery, the faster they grow." Brinker shaved 7-10 days off finishing time based on bigger pigs coming out of the nursery. PRDC Programs

Rodibaugh offers the following approach to consider when working with your veterinarian to develop a program to beat PRDC.

* Identify the pathogens present to select the appropriate management tool.

"Producers can't afford indiscriminate use of antibiotics, so be sure the one you choose has activity against your problem organism(s)," Rodibaugh points out.

* Examine where disease typically strikes and position products where they will do the most good based on your operation and management style.

* Determine how you will define success and judge accordingly.

"There are many ways to define success such as reduced clinical disease, less mortality, fewer injections, performance and pig flow issues. Every farm is different so decide what success means to you and decide how you will measure if your program is working," he advises.

For Townsend and Brinker, success means knowing what PRDC organisms they are up against, and fighting back with an effective program that brings pigs out of the nursery healthy and ready to grow in the finisher.

"My philosophy is that the most expensive antibiotic program is one that doesn't work, so a program here is judged on the success we have with it," Townsend concludes.

For an antibiotic to be effective in a pig's body, it must navigate the animal's system to reach the bacteria.

Researchers at Elanco Animal Health discovered that tilmicosin, the active ingredient in Pulmotil, operates with a unique mode of action that delivers the drug to the bug.

Unlike most other products which are transported by blood and remain in it, Pulmotil works at the cellular level. It closely targets diseased tissue where bacteria resides, the prime spot for antibacterial action to take place.

The product concentrates in the macrophage, a key cell in a pig's defense mechanism network, and thus works in concert with the immune system to travel to the source of infection.

The tilmicosin-loaded cell surrounds and engulfs bacteria, allowing the drug to directly contact the bacteria and kill it.

This mode of action is unique to macrolide antibiotics and allows the animal's immune system to regain the upper hand.