Friday, February 29, 2008 7:48 PM CST
By Huey Freeman
BLOOMINGTON -- How do you perform a root canal on a 225-pound Sumatran tiger? Very carefully. Video Photo gallery
Dr. Larry Baker, a Decatur-based veterinary dentist, worked alongside a human endodontist, three veterinarians, a veterinary technician, a human dentist, two dental assistants and two veterinary students, to repair a broken lower canine tooth of Besar, a 16-year-old Sumatran tiger.
The impressive array of top-notch professionals who turned out to drill and fill the powerful cat's root canal Friday appeared firmly in control for most of the two-and-a-half hour procedure.
But there was a tense moment when the tiger's survival seemed threatened.
When dealing with an animal that is not particularly friendly to people -- and capable of quickly killing with its powerful jaws -- it is important to make sure that such a creature sleeps deeply while someone is working inside its mouth.
"He hates everybody," said veterinary technician Linda Sax, describing the tiger's special relationship with his keepers. "Everybody is scared of him when he wakes up."
The trick is to give the animal plenty of anesthetic so it remains unconscious, but not too much so that it stops breathing or its heart stops beating. That is why three or four people were closely monitoring vital signs at all times.
Before the procedure began, the Miller Park Zoo superintendent quietly informed Baker there was a back up plan which hopefully would not be needed.
"In that room there's a shotgun -- just for safety's sake," John Tobias said, pointing to a door in the operating room of the zoo's new hospital.
But Baker, a self-described risk taker who has performed hundreds of root canals on dogs and smaller cats, was not shaken by the potential danger.
"I was very confident," he said after the operation. "I figured I could move as fast as anybody else."
However, Dr. Keith Evans, a Bloomington endodontist, acknowledged that he was a bit concerned when the tiger seemed to be stirring near the procedure's conclusion.
"There's no anesthesia," Evans said afterward. "And the tongue is moving and my hand's still in his mouth."
The anesthetic, isoflurane, was administered to Besar, along with oxygen, throughout the procedure through a tube inserted in his trachea. But when a veterinary student proclaimed that his heart rate had dropped to 60 beats per minute and his breathing appeared to dramatically slow down, the anesthetic was shut off.
"Can everyone be quiet for a moment while she listens to the heart," said Dr. Mark Mitchell, a University of Illinois veterinary professor.
The noisy operating room suddenly went silent.
Then veterinarian Dr. Jeanette Romanowski of Normal, listening through her stethoscope, announced, "84," an acceptable heart rate for an anesthized tiger.
Sax, who was monitoring the tiger's breathing, said she had stopped the anesthetic. About two minutes later Evans felt the tiger's tongue move around, and began working furiously to complete filling the root canal with cement.
Sax, who works at Prairie Oak Veterinary Center, which provides care for the zoo inhabitants, said Besar's broken lower left canine tooth was first noticed a year ago. Besar, who was given pain medications and anti-biotics, did not exhibit signs of suffering.
"Animals can't show pain in the wild," Sax explained. "If they show weakness other animals will come and eat him, even though he's a tiger."
After Baker, the only veterinary dentist in Central Illinois, was contacted late last year to work on Besar, he ordered a new portable X-ray machine, which is especially lightweight and safely held for close range work. He also bought a long set of files, which are very helpful for cleaning out the three-inch-long roots of tiger's teeth.
The X-ray machine, which was much admired by the other human and animal care professionals, produces an image on a computer screen in six seconds, helping tremendously with diagnoses and treatments.
While Baker was at the zoo, he also worked on a root canal and removed a tumor from the lip of Chapin, a 24-year-old, 329-pound sun bear.
"It was pretty easy," Baker said. "We were a little concerned he would wake up when he was taken off the anesthetia machine, but he didn't. There were no problems."
Tobias was pleased that the first procedures to take place at the zoo's new hospital went so well. It is equipped with a large window, to enable visitors to view some of the veterinary work.
"I think it is great they all came out here," Tobias said of all the people who worked on the animals. "They're getting the experience working on the tiger and the bear and we're getting health needs taken care of."
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