Researchers learn new technique
By Eric Hand
Of the Post-Dispatch
Nine women, a Norwegian veterinarian and two Mexican gray wolves were crammed together Sunday in a tiny trailer at the Wild Canid Survival and Research Center in Eureka.
The anesthetized wolves, tongues lolling, were certainly calmer than the researchers, who passed catheters and syringes around the tight space, hoping to help a male wolf named Dude impregnate a female named Nikomis.
Last week at the center, Norwegian veterinarian Ragnar Thomassen completed the first intrauterine artificial inseminations of an endangered species.
His technique, at least two or three times as good at producing pups as conventional ones, will give the west St. Louis County research center another tool in its ongoing effort to bring the Mexican gray wolf back from near extinction.
In the late 1970s, a U.S. Fish and Wildlife Service trapper caught the last five wild Mexican gray wolves from their high terrain in Arizona, New Mexico and Mexico. The Mexican gray wolf is a genetically distinct subspecies of the more common gray wolf.
The animals arrived in 1980 at the research center, a 65-acre sanctuary within Washington University’s Tyson Research Center, along with a few Mexican grays from zoos. The first captive-bred pups were born in 1981.
Every Mexican gray wolf in existence can trace its genetic lineage through the center, said director Susan Lindsey. Lindsey says there are now 240 captive wolves, and about 60 have been released to the wilds of Arizona and New Mexico.
Since the wolves come from only a handful of founders, zookeepers want to breed for genetic diversity, which lets animals adapt and fight disease better, said Edward Spevak, a Cincinnati Zoo biologist. Spevak uses matchmaking software that crunches the entire wolf family tree and every year picks the wolf couples that would produce the most genetically prized pups.
“But animals don’t always do what you tell them to do,” said St. Louis Zoo research director Cheryl Asa. She noted that wolves tend to take one mate for life. Also, she said, moving a wolf to a different zoo for a blind date is expensive and hard on the animal.
Artificial insemination is simpler. Semen can be frozen, stored and transported cheaply. But the conventional insemination technique – where semen doesn’t get past the cervix and into the uterus – isn’t very successful. It only works about 20 percent to 40 percent of the time, Lindsey said.
Researchers have better luck with surgical techniques – where semen is injected into the uterus through a small abdominal incision – but they don’t want to run the risk of infection with an animal that is unruly, dirty and hard to monitor.
That’s why Asa and Lindsey brought Thomassen to St. Louis – so he could teach local researchers his intrauterine technique. It requires the delicate passing of a catheter through a bean-sized cervix, then injecting semen through the tube. He said his technique produced pregnancy up to 95 percent of the time – as good as natural mating.
Thomassen used the technique to inseminate two female wolves last week. On Sunday morning, the researchers were ready for Nikomis, the last of the three females, on the day she was expected to ovulate.
Assistant center director Kim Scott collected Dude’s semen in a plastic cup after the wolf was stimulated electrically. “Good boy,” Scott said, patting the wolf’s chest after he had produced a half-dozen small samples.
The researchers moved Dude out by his furry scruff and put Nikomis in place. Thomassen gave advice to St. Louis Zoo lab manager Karen Bauman, whose eyes were closed in concentration as she tried to slip a footlong catheter past the wolf’s cervix.
“It’s like threading a needle, but you can’t see the hole you’re trying to thread,” she said, after wiping sweat from her brow.
Lindsey said she would know in a month if the three females were pregnant.
The Mexican gray wolf, a genetically distinct subspecies of the more common gray wolf, is the rarest and most-endangered wolf species in the world.
Weight: 80 pounds.
Size: Up to 5 feet long, about the size of a German shepherd.
Range: Before last century, the wolf could be found in Arizona, New Mexico, Texas and Mexico.
Speed: Up to 35 mph.
Reproduction: Once a year, litters of four to six puppies are born after a pregnancy of two months.
Prey: White-tailed deer, mule deer and elk.
Population: About 240 in captivity and 60 released to the wild.
Goal: The U.S. Fish and Wildlife Service wants a wild population of 100 wolves.
Sources: U.S. Fish and Wildlife Service; Wild Canid Survival and Research Center