Preventing Deformed Snouts in Pigs

A pig with a deformed snout won't be a hot seller in the marketplace. When nasal deviations occur among porkers, it usually means disease—and extra production costs.

A 1990 USDA survey of Iowa pig farms showed that Atrophic rhinitis, a bacterial disease, cost producers about $4 million a year for vaccines, medications, and death losses.

"This is an insidious disease that lowers profits by reducing weight gains and lengthening the time that it takes to get hogs ready to market," says ARS veterinary pathologist Mark Ackermann. "Worse yet, there is no cure. Prevention is always the best route."

Ackermann and other researchers at the National Animal Disease Center (NADC) in Ames, Iowa, have studied the disease for the last 7 years. Atrophic rhinitis is highly contagious and easily spread among pigs in confinement houses. Currently, about 40 percent of all producers vaccinate sows and nearly 30 percent vaccinate pigs.

The disease is caused by toxins produced by two bacteria—Pasteurella multocida and Bordetella bronchiseptica. Previously, researchers thought the Pasteurella toxin might suppress the pig's appetite, resulting in weight loss. But the NADC research team of Ackermann, molecular microbiologist Karen Register, veterinary pathologist Sharon Gwaltney, and technician Kim Driftmier confirmed that the toxin actually reduces long-bone growth.

They also found several toxic strains of P. multocida lurking in the tonsils. Finding the bacteria in the tonsils was important, because not all infected pigs have deformed snouts. Still the disease makes them weak and vulnerable to other diseases, such as pneumonia.

This NADC team has developed new diagnostic tests to identity toxic strains of P. multocida and a DNA probe to genetically identify B. bronchiseptica.

"Commercial vaccines are effective if the producer selects the right one. A good choice for a vaccine should contain a denatured Pasteurella toxin, called a toxoid, which can provide immunity without causing disease," says Ackermann.

The NADC researchers have demonstrated the effects of protecting pigs against toxin. In studies done last summer, pigs with immunity to toxin gained weight normally and didn't develop nasal or long-bone deformities.

Ackermann says that vaccination with a good combination of bacteria and toxoid should lower the number of bacteria in the environment. "Some of the commercial vaccines on the market don't have the toxoid component, so producers should carefully check the label before relying on a vaccine to protect pigs," he says. — By Linda Cooke, ARS.

"Preventing Deformed Snouts in Pigs" was published in the November 1995 issue of Agricultural Research magazine.