A Root Canal for Kenai
During sea otter Kenai’s head-to-tail annual physical exam last year, the veterinary team noticed a crack in her left upper canine tooth. “So we took digital radiographs of the teeth and skull,” says Dr. Lisa Naples, one of Shedd’s veterinarians and section chief of conservation medicine. “Just like when you go to the dentist, when they do their routine radiographs of your teeth, they can see if a tooth is healthy or not.”
In this case, she says, the X-rays clearly showed “that there was a problem with the root.”
A sea otter’s canine teeth are impressive. They belie the image of a cute, furry imp playfully tumbling and twirling in the water. They say “carnivore.” “This is one species of animal that relies heavily on its teeth for cracking, crunching and chewing food,” says Dr. Naples.
The next step was to call in a specialist. Dr. Stephen Juriga is a veterinary dentist specializing in endodontal work—like root canals—and he’s a member of Shedd’s medical advisory board, a team of human and animal practitioners who volunteer their time to help maintain the health of the aquarium’s animal collection.
When the dentist examined the anesthetized otter, he saw that in addition to the fracture, Kenai had signs of gingivitis around the tooth. “The rest of her gums looked pretty good,” says Dr. Caryn Poll, Shedd’s section chief of medicine, “but she had a lot of inflammation around the tooth. We were concerned that we wouldn’t be able to save it.”
At this point, some people might wonder why the veterinary team didn’t opt to remove the tooth. Dr. Poll points to a radiograph of Kenai’s choppers. “It’s not a trivial thing to extract a tooth on these animals because the roots go practically up to the eye sockets. The canines are really big teeth, so they need really big roots.” Saving the tooth would have two benefits, she says: It would allow Kenai to keep the tooth so she could keep eating with it, and a repair would be less invasive than an extraction.
Happily, the tooth was salvageable: It was still secure in the socket, and the inflammation around it was treatable with antibiotics. Dr. Juriga concluded that the best course of action would be to proceed then and there with a root canal.
Before the dentist even set foot in the aquarium, however, a collaborative effort was in motion to provide him with a wealth of preparatory materials.
“These cases are good examples of collaboration from everyone,” says Dr. Naples. “The animal husbandry staff members at Shedd are experts at behavior and life history of the sea otters, and they can contribute information on feeding behavior, activity levels and how the animal is doing before and after the procedure. We contribute our expertise in anesthesia with this species, the anatomy of this species and the overall medical picture. Dr. Juriga contributes his expertise dentistry-wise.”
Dr. Naples even tapped colleagues at the Field Museum, who lent her a sea otter skull with normal dentition to X-ray. “The structure of a sea otter canine is completely different from a canine on another carnivore, like a polar bear or a tiger,” she says. “The skull helped Dr. Juriga identify the root depth and length.”
The anesthesia had its own game plan. “Any time you anesthetize an animal, you want to be prepared for any eventuality,” says Dr. Poll. “We have a very safe protocol that’s been developed using a combination of injectable narcotic drugs. The animal goes to sleep, and you give it a reversal, and it wakes up. We also bring gas anesthesia to help us fine-tune the depth of anesthesia, and we’re prepared with equipment and training to breathe for the animal if needed. We’ve got all of our medical necessities right at our fingertips.
“The important thing is to look ahead to what might be a complication and then just be prepared for it. We talk through what the procedure is going to be, work up extensive equipment lists and assign roles: who is going to be doing anesthesia support, who’s going to monitor body temperature, who’s doing blood collection. We each have a role, and we know what that role involves. It’s very important.”
So is having enough ice on hand.
While she was anesthetized, Kenai was nestled on a bed of ice. Dr. Poll explains, “These animals are not designed for warm temperatures. Their fur contains a million hairs per square inch, and the concern under anesthesia is that they might overheat. So we make them an ice bed to keep them cold, and we monitor their body temperature so we can regulate it by adding or removing ice.”
Once Kenai was safely anesthetized, the team took radiographs of her jaw to compare with the images they had of the skull from the Field Museum.
Then the actual root canal could begin. “While the size and shape of teeth vary greatly, the procedure is the same for people, dogs and sea otters,” Dr. Poll says. The dentist inserted a probe into the infected tooth to measure how far down the root extended and how much filling he’d need. Then he scrubbed out the center of the tooth, removing nerves, blood vessels and what can only be called “gunk.” After thoroughly disinfecting it, he packed the now-hollow tooth with gutta-percha, a natural latex product that’s also used in fillings.
Throughout the surgery, the team took digital radiographs—immediately viewable on a nearby computer screen—to make sure no air spaces or fluid pockets were left inside the tooth. Dr. Juriga finished the job by restoring the tooth with a dental composite. This material is used in human and veterinary dentistry to seal a tooth after a root canal. It's durable and resistant to the wear and tear of eating and chewing—and cracking clam shells.
The exam and root canal took two hours. “Dr. Juriga made it look easy,” says Dr. Poll. Both veterinarians had high praise for the dentist’s skills as well as his for generosity in donating his services to Shedd.
Kenai had her usual early evening meal the night before the root canal, but no breakfast. “The procedure was first thing in the morning so that as soon as she woke up, she could be fed,” says Dr. Poll. “And she was up and eating on the tooth right away.” That indicated to the doctors that the pain-control medication—a nonsteroidal anti-inflammatory drug—was adequate.
“It’s important to make sure after a procedure that an animal starts eating again,” Dr. Poll says. “Especially with a sea otter, with this species’ high metabolism, the animal needs food frequently, so you want to make sure there’s no pain to keep her from eating.”
The teamwork continued as the marine mammal trainers monitored Kenai, checking inside her mouth during training sessions and, as always, meticulously recording how much food she ate by weight. “If anything ever comes up that’s of concern to the marine mammals staff, they let us know right away,” says Dr. Poll.
She continues, “We’re very happy that we were able to salvage the tooth. You can always pull it at a later date if you need to, and Kenai could function without it, but it’s better for the animal to save the tooth, especially something as prominent as a canine. It maintains her normal eating patterns. And she’s done exceptionally well since the procedure.”
Kenai’s root canal points up the importance of Shedd’s preventive healthcare program for all of the animals. Without detection during her wellness exam, the infection could have progressed to the point that she had difficulty eating. Then the trainers would have noticed and called in the healthcare team, but catching the tooth infection early saved Kenai that distress and also avoided exposing her to a secondary infection of her heart valves, a frequent complication of severe dental disease.
In addition to benefiting from the advances in veterinary dentistry, Kenai is a living testament to the emerging field of geriatric veterinary medicine. With excellent preventive and urgent care, aquarium and zoo animals are living healthier and longer lives. At 22, Kenai is one of the two oldest sea otters in North American animal collections.
Her health records—weights, blood test results, radiographs, dental work—not only make up part of Shedd’s database on her as an individual and on the sea otters as a species, but are also submitted to ISIS, an international database on aquarium and zoo animals. This vast shared body of information provides veterinarians with reference values for the gamut of exotic species.
“There’s still so much to learn,” says Dr. Naples. “We rely on information from other aquariums and zoos, and we rely on information from fieldwork and research.” Ultimately, she says, what’s learned at zoological organizations is also applied to conservation of the same species in the wild. This is especially true of Kenai, a survivor of the Exxon Valdez oil spill, who has been part of long-term studies on the sea otters exposed to oil—still a risk in the wild.
Dr. Juriga has used his rare opportunity to do dental work on a sea otter to share what he’s learned with colleagues at veterinary dentistry conferences.
Maybe not all root canal procedures are alike after all. Kenai’s has a silver lining, figuratively speaking, for sea otters in aquariums everywhere and for the medical teams who take care of them.
—Posted by Karen Furnweger, web editor