By Jeff Caldwell

Halfway through the first decade of the 21st century, many believe the hog industry has morphed into a business of giants, no longer a place where the small-scale producer can compete.

But, in view of the cutting-edge work that is going on at one rural Iowa veterinary clinic, a strong case can be made for the opposite. One day, operators of 100-head farrowing units may be on the competitive level of their 6,000-head industry counterparts, with the overall agricultural economy, and most importantly, humankind, being the ultimate benefactors.

Struve Labs, in Manning, Iowa, by all outward appearances, is not unlike most small-town veterinary clinics. But, the work that Rexanne Struve, DVM, and her staff of technicians, carries out is done in no other private commercial practice in the U.S.

Struve, a 1976 graduate of the Kansas State University College of Veterinary Medicine, purchased clinics and laboratories in Manning and Manilla, Iowa. She set out to continue work her predecessor began in 1961: To furnish healthy, Specific Pathogen Free porcine breeding stock to individual hog producers, the first work of its kind in Iowa.

As Pseudorabies virus ravaged the Iowa swine herd in the 1980s, Struve saw increased demand for clean breeding stock, as many producers were forced to depopulate their own herds in an effort to rid the state of the virus that was eventually declared eradicated from the state's swine herd in 2004. Despite the clinic's growth during this time, producing SPF pigs wasn't always the most popular operation. When managed and cared for incorrectly, the lab-derived stock could not survive on the typical small hog farm, something that gave the SPF program a bad name.

"People would go out and buy clean SPF boars and throw them in with a bunch of dirty sows, and the boars would die. It wasn't the boar's fault, but they blamed the SPF program for that," Struve says. "They are cleaner, but they don't have as good an immune system."

A physiological glance

at SPF pigs

Originally started as a way to provide "clean" pigs to producers wishing to start or restart herds, the SPF program began in the 1960s, with Merrick Labs, the predecessor to Struve Labs, leading the charge in Iowa. The animals' qualification as "clean" refers to the immune system. Reared and raised in a laboratory setting, void of viruses, pathogens and some bacteria that are typically present pigs' bodies early in life, they at first lack the immune function to take a place in a conventional hog herd. During the early stages of life, the animals are slowly introduced to these disease-causing agents, like mange, lice, PRV, Parvo virus and Cipro virus, fostering the animal's adaptation over time, ultimately yielding immunity to these conditions stronger than that resulting from natural adaptation. According to Struve, oftentimes SPF pigs are mistaken for a similar program that, while it yields pigs under similarly disease-free conditions, is altogether different.

"The interesting thing about the SPF program is that the SPF name was used for so long that some of the researchers use the term, but don't know what it means," she says. "SPF is not the same as gnotobiotic, which means no bacteria, no viruses or no pathogens at all. That's not this. Those pigs have to stay in a bubble their whole lives. Specific Pathogen Free can mean all sorts of different things."

The final result of SPF production is a pig that, when introduced into a larger herd, is naturally more strongly immune to the most common viruses and diseases that afflict the animals without the need for antibiotics or vaccines. Since the animals aren't required to exert energy to bolster the immune system later in life, they have a higher rate of gain and can be sold to the slaughter market faster.

As the first-generation additions reproduce, each subsequent generation of offspring has a stronger immune system than the one prior. In this sense, rearing pigs that, at first, have very weak immune systems ultimately yields a herd that is free from viruses that can otherwise decimate the animals.

Building on SPF pigs

After starting with SPF pigs, Struve began working with Cesarean-derived, colostrum-deprived pigs. Essentially a step beyond SPF pigs, they possess the same disease resistance, only to a greater extent. Without passage through the mother's birth canal and nursing from the mother's colostrum, the newborn pigs are completely free of resistance to pathogens, viruses and many bacteria, since bacteria can be picked up during conventional delivery, as the animal passes through the mother's placenta. Without nursing the mother's colostrum, the milk produced during the first 24 hours after birth, the animal's natural immunity is not passed along to its offspring.

"The big reason mothers should nurse children, whether human or animal, is because they get antibodies from the mother," Struve says. "The first 24 hours' milk, or colostrum, is very, very high in antibodies, vitamins and other things that protect the babies."

As a result, CDCD pigs share SPF pigs' vulnerability to disease in the early stages of life.

"They are extremely susceptible to diseases, so you cannot take clean pigs that come out of our lab, put them in with dirty pigs and expect them to live, because they'll die. They don't have the immunities."

The importance

of CDCD pigs

The value of natural disease resistance that the CDCD pigs have by five- to seven-weeks of age goes well beyond any amount of money a producer can save without the animals requiring most antibiotics or vaccines. What begins in Struve's lab could ultimately end up with a man, woman or child crossing his or her name off an organ donor list. Xenotransplantation, or the use of one animal species' organs in another's body, has been taking place, in past years, only on smaller scales, either with clusters of cells or tissues.

"It may be as simple as running someone's blood through a machine that has a pig pancreas or pig liver in it," Struve says. "Right now, they can take heart valves and ligaments out of pigs and put them in people, but the body doesn't reject those like it would a heart or liver, because they are a collagen matrix, and they don't have as much cellular components and blood supply. People have been using pig heart valves for 30 years."

Moving a step beyond these methods of xenotransplantation, the pigs reared in Struve Labs, by virtue of deprivation of colostrum and delivery by Cesarean section, are transgenic. This means they have, through essentially natural means, been altered at the genetic level to yield specific traits. The resulting animal has organs that are "clean," possess human genetic traits and can be wholly used for transplantation into men and women whose own organs are in need of replacement.

"Even though we've been doing this for a long time on smaller levels, we haven't been able to take a whole heart or liver and put them in a baboon or human, because they'll die," Struve says. "The transgenic animals are being developed to carry the human gene, so that humans will not recognize those organs as a foreign animal body part."

One porcine-derived

medical device

One way that porcine cellular material is being currently used for the salvation of human life is through the use of islet cells. According to Struve, the islet cells are those that produce insulin in the pancreas, ultimately controlling glucose levels in the bloodstream. Without these cells functioning properly, diabetes results.

Islet cells from CDCD pigs can be placed into a titanium capsule and placed either under the skin or in the peritoneum, the tissue that encircles thoracic organs, and when blood sugar levels climb too high, they interact with the bloodstream, beginning to produce insulin to balance out the blood chemistry. In this case, with the islet cells being encased in titanium, which is virtually non-reactive to human organ tissue, the process doesn't qualify as true xenotransplantation.

"Without the pig cells actually being in the body, they're inside these devices, but still doing their job," Struve says. "Right now, the need is for organs, especially livers and pancreas out of clean pigs that can be used inside medical devices like these. Ultimately, we'll end up with transgenic animals where we can implant organs, but now we're just using medical devices."

Ramifications to

tomorrow's hog industry

Even though the most common vision when the general public thinks about today's hog industry is a multi-thousand-head feeding facility, the opportunity CDCD pigs for xenotransplantation represents may forever change the landscape of the industry. In the future, with the development of the medical-grade animals, the production of transgenic CDCD pigs will be done in small units where conditions can be precisely monitored. The financial effects of this type of production could be tremendous.

"You have to raise these animals in small groups, where you can contain them better, monitor and control them, and if something happens, you haven't lost a year's worth of production or left someone waiting for a heart or liver," Struve says. "The value of the trickledown effect in the medical field is one thing, but the trickledown effect to the economy is another, because we would have whole family farms that would be built around these pigs.

"It would be extremely financially lucrative for the producers. The price is extremely high for these medical-grade pigs."

The industry segment's development will come at costs, however. Models for infrastructure and production procedures must be established to make raising transgenic CDCD pigs a worthwhile venture. This includes comprehensive management that, despite its necessity, could become a larger task than what some producers can handle.

"There has to be an infrastructure for this, and that's what we're looking to do. We want to get the model out there and get producers started first of all," Struve says. "So many things have to be monitored, and a producer has to know the amount of paperwork that goes into something like that. It's just like in human hospitals--it can become inundating. It's not something you can have somebody do as a part-time deal. Someone has to be responsible for that all of the time."

General economic effects

In spite of the tremendous opportunity transgenic CDCD hog production for human transplant poses for the industry, the effects upon the economy in general could be equally substantial. With the amount of infrastructure necessary for both the production and management of medical-grade pigs, jobs will be created throughout areas where the small facilities dot the landscape. While the jobs will be larger in number, it will be the skill level and pay that will affect the economy most.

"We have a real interest in bringing better jobs into the area. Besides raising the pigs, they go through a quarantine process before they are used for medical purposes," Struve says. "When this is done with hundreds of animals at a time, hospitals will have to operate to do that work. This will bring in high-paying, skilled and long-term jobs--the kind we're working to bring in."

To this point, Struve is taking steps, alongside both industry officials and government officials, to introduce CDCD hog production further into the state of Iowa, in hopes the industry, which has been important to the state's economic past, will gain a stronger foothold in Iowa's overall economic future.

"There are fantastic opportunities here if it's put together right and started up properly," Struve says. "We should raise pigs in Iowa. We should raise them here, and raise them for whatever they need to be raised for."

Humankind the ultimate benefactor

Altogether, the percentage of the U.S. population involved in the hog production industry is extremely small. Yet, the production of transgenic CDCD pigs for xenotransplantation in the future will affect virtually every American, whether through the procurement of a life-saving organ, or that for a friend or family member. If the industry Struve has begun in Manning, Iowa, is able to progress in the future, the landscape of modern medicine could change forever.

"There will be small production units like this all over. Ultimately, we could have a mass production system where we could have hospitals where the organs of 'clean' pigs are matched up to people," Struve says. "It will take just a few minutes to do a transplant. We can ship hearts to Kansas City, or lungs to New York--whatever people need."

Jeff Caldwell can be reached by phone at 515-280-5405 or by e-mail at jcaldwell@mchsi.com.

Date: 1/27/05

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