LSU AgCenter animal science researcher Glen Gentry gives an update on his work with sodium nitrite as a toxicant for controlling feral hogs. His presentation was part of the Fall Symposium on Recent Natural Resource Research in Louisiana on Aug. 29 in Baton Rouge. (Photo by Johnny Morgan)

BATON ROUGE, La. – With annual damage estimates at nearly $1.5 billion nationally, and with a population of over 400,000 in Louisiana, wild hogs drew wide interest at a natural resource symposium on Aug. 29.

The meeting devoted a day of the program to focus on what was called “Louisiana’s feral hog invasion.”

LSU AgCenter animal science researcher Glen Gentry gave an update on the work that he’s doing with sodium nitrite as a toxicant for controlling feral hogs. He is testing different flavors that attract pigs, which is proving to be more difficult than first expected.

“What we are finding is that pigs are attracted to certain flavors, such as strawberry, which they seem to like,” Gentry said. “However, the grain-based bait has some problems.”

When the sodium nitrite is added to the mix, consumption tends to drop off, he said.

“We are looking at semi-solid bait forms developed by LSU AgCenter researcher Zhijun Liu in the School of Renewable Natural Resources,” Gentry said. “I like using gummy bears as a way to hide the salty and bitter taste of sodium nitrite.”

Sodium nitrite is effective in taking the oxygen out of the pig’s blood through the formation of methemoglobin. The process causes them to become drowsy, lie down and expire, Gentry said. At the right level, this will happen in most mammals, but deer and some other animals are less sensitive to the chemical.

“All mammals, including humans, have an enzyme that is able to change methemoglobin, which cannot bind oxygen back to hemoglobin,” Gentry said. “But pigs don’t have as much of this enzyme, so it takes less sodium nitrite to overload their system.”

Gentry said his study is mainly looking at three things: the effective lethal dose of sodium nitrite, an effective delivery medium and an effective and selective delivery system. Laws and regulations say that the poisons must be publically acceptable and produce a humane death.

“Sodium nitrite is basically a food preservative and is also used as an antidote for cyanide poisoning,” Gentry said. “When using sodium nitrite, the animal suffocates from the inside out.”

The goal is to kill 90 percent of the pigs. So far, Gentry is at 68 percent.

Other topics at the meeting included wild pig reproduction in Louisiana, movement of wild pigs in Louisiana and Mississippi, and restoration of freshwater marsh by lethal harvest of feral hogs via helicopter.

The program also included a panel discussion of ways to coordinate a response to Louisiana’s feral hog problem.

One of the major problems faced by landowners is feral pigs are being transported to areas that may have not had them before, according to James LaCour, wildlife veterinarian with the Louisiana Department of Wildlife and Fisheries.

“Hogs are definitely being moved around,” LaCour said. “It’s legal to transport wild hogs, but it is illegal to release them back into the wild.”

Chad Corville, manager of Miami Corporation, a holding company that owns 240,000 acres of coastal marsh, agrees that moving wild pigs around is a problem, but it is worst in inland areas than in marsh areas.

“In the marsh, when they reach capacity, they move on their own,” Corville said. “A big problem they cause in our area is when they root up alligator nests.”

Corville said when the wild pigs come into an area, they cause deer, squirrels, turkeys and other game animals to leave, and soon “all you’ll have is pigs.”

The group agreed a campaign should be developed to provide talking points to legislators.

Randy Lanctot, retired executive director of the Louisiana Wildlife Federation, said he agrees a campaign is needed to get the word out. He proposed the creation of a picture book of the “Big Bad Hog.”

“We need to show this animal in a very negative light to the decision-makers,” Lanctot said. “They need to see that this is a bad animal.”

The annual meeting held at the Waddill Outdoor Education Center in Baton Rouge was sponsored by the Louisiana Association of Professional Biologists and the Wildlife Society Louisiana Chapter.

Johnny Morgan