Wednesday, April 25, 2012

Brookfield Zoo's wolves go into lab for nasal cancer study

Brookfield Zoo's wolves go into lab for nasal cancer study


It is not a scene you expect to witness: a wolf, out cold, immobilized, its feral snout inside the giant doughnut ring of a high-tech medical device.
It's also striking purely on the level of language: a canine in a CAT scan.

But the CAT acronym, of course, has nothing to do with animals. It stands for computerized axial tomography, and on this day late last week at Brookfield Zoo, the institution was using the internal imaging technology common in human medicine to check the third, fourth and fifth members of its Mexican gray wolf population for nose cancer. Two others have already completed the process, and the scene will repeat Wednesday, when the last three of the zoo's eight wolves are scheduled to get the high-end treatment.

One thing was clear: Whatever else is going on in American health care, these patients have a pretty good coverage plan. Minimal wait times. Attentive, abundant staff. No discernible co-pay, unless an hour or so of unconsciousness counts.

They were separated from the pack temporarily, true, but they might have felt at home nonetheless. Around them in the west suburban zoo's medical rooms swarmed print and television reporters, cameramen and photographers, a different kind of pack.

Brookfield is leading, and publicizing, a study of the Mexican wolves — a smaller, endangered subspecies of the North American gray wolf — in hopes of determining potential causes of a higher-than-expected incidence of nasal carcinomas in the animals.
The rare peek into the zoo's backstage area not only showcased a magnetic animal in extraordinary circumstances. It highlighted the kind of work that goes on regularly as zoos, beyond the display function that the public usually thinks about, further their roles as wildlife conservators and research institutions.

The Mexican wolf situation illustrates some of the potential complications of captive breeding plans. Their subspecies nearly extinct in 1980, seven captured animals have yielded a captive population now numbering 258, plus another five dozen living in the wild, in the Southwest. Such a small starting point has raised concerns about whether the genetic diversity is adequate.

"We are trying to understand what is the role the genetic links play, if any, in the nasal tumors," said Dr. Carlos Sanchez, an associate veterinarian at Brookfield and a leader of the study. "Are we seeing more cancer in this animal because they are inbred, or not really?"
Four-year-old female siblings who came to Brookfield in 2010, the wolves enter the study rooms one at a time, about an hour apart, carried, unconscious, in a big sling. A sign at their exhibit, on one end of the park, explains that 10 a.m. is usually among their most active times. Not this morning.

Carefully transferred to an examining table, they get more than just the CAT scan. In the normal course of things, such animals would be examined every two or three years, more frequently only if the need arose.

So taking the trouble to put them under means staff seize the opportunity to give them all full physicals, including blood work and heart and lungX-rays, plus a grooming treatment similar to what the wolves' domestic cousins receive: nails clipped, ears and teeth cleaned — everything but the cute haircut and jaunty bandana tied around the neck at the end.
And before the CAT scan, there's another research project to contribute to. The USDA in Arizona, where other Mexican gray wolves have been released into the wild, wants to know the distance between the upper and lower canines. The veterinary staff open the jaws and, with a calipers, make the measurements.

The data, in conjunction with close examination of bite marks on downed farm animals, will help determine which predator is responsible and whether the agriculture department will compensate farmers for their losses.
"They can say, 'This is not a wolf. It was a puma,'" Sanchez explains, information that could keep the wolves safer. Coyotes, of course, are also present in their habitat, and "feral dogs are the No. 1 cause of problems," he said, but wolves, given their popular reputation, are often first to be blamed.

The reality of these Brookfield wolves, which zoo staff have given names such as Francena and and Nancia, is of course milder than the great vengeful beasts and savage, slobbering were-creatures of fiction.
It is a dangerous notion to have, but, laid out on a table, their blond and salt-and-pepper coats gently heaving, they really do look, and smell, like dogs. The similarities are perhaps more pronounced with the Mexican wolves, which, smaller than their gray wolf brethren, top out at about 80 pounds.

After the X-rays, they are wheeled down the hall to the CAT machine, one of only two, Brookfield staff believe, on site at a U.S. zoo.
The study began because some 14 nasal tumors have been found in Mexican gray wolves, said Peter Siminski, director of conservation and education at The Living Desert in Palm Desert, Calif., who directs the wolves' Species Survival Plan for the Association of Zoos and Aquariums.

In addition to looking at the live animals, the study will see Dr. Sanchez and Dr. Randi Drees, a veterinarian from the University of Wisconsin, put the preserved skulls of 175 Mexican gray wolves under the CAT scan as they are shipped to Brookfield in coming months.
This will give a better picture of the history of the tumors in the known population. If a genetic link is ruled out, scientists will have to look more closely at other potential causes for the cancers, including environmental and viral.

As the animal is in the machine, Drs. Sanchez and Drees are just outside in the hallway, taking a preliminary look at the results on monitors. (They'll look more closely later, including with the aid of new software that creates a 3D image of the skull.)
The encouraging results will be similar for the first five Brookfield Mexican grays, Sanchez will later say, although one animal will be found to have a slightly deviated sceptum, a normal biological variation.

"They can't tell us they have something in their nose which is bothering them, so for us, this is the perfect way to look into their nose," says Drees, looking at the monitor. "This is absolutely how we want to see it … The white structure, those are the bones. They're normal. They're intact. And then in the middle here we have mainly air."
"This," Sanchez adds, "is now a normal nasal cavity is supposed to look."
 Video available here at source