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Medical professionals bring their expertise to the National Zoo to help care for the animals
by Phyllis McIntosh
What started as a routine checkup on a ten-year-old ring-tailed lemur quickly turned into a medical mystery when an X-ray revealed fluid in the animal’s lungs. Why was an otherwise healthy primate showing classic signs of congestive heart failure? To help investigate, Smithsonian’s National Zoo veterinarians called in ultrasound specialist Cynthia Sloan and cardiologist Steven Rosenthal from veterinary clinics in the Washington area. They discovered an important clue: “buzzing,” or vibration, in the animal’s groin, which signals an abnormal connection between an artery and a vein that causes the heart to work overtime to pump blood to the tissues.
To repair the problem, the vets turned to doctors who have vast experience operating on small bodies with similar anatomy: Kurt Newman, chief of surgery at Children’s National Medical Center, and his colleague, pediatric vascular surgeon Philip Guzzetta. Their patient recovered and is now enjoying life on the Zoo’s Lemur Island.
|Veterinary resident Margarita Woc-Colburn monitoring
anesthesia for a zebra. (Mehgan Murphy/NZP)
This is just one example of how the Zoo’s veterinarians join forces with local physicians and veterinary specialists to provide the best possible medical care for the Zoo’s residents. National Zoo chief veterinarian Suzan Murray has a working relationship with at least 15 outside specialists—surgeons, cardiologists, dentists, dermatologists, anesthesiologists, gastroenterologists, neurologists, oncologists, immunologists, urologists, and ophthalmologists—to whom she can turn for assistance. All of them volunteer their time to help the Zoo.
“As specialists in zoological medicine, we can perform most procedures on our own,” says Murray. “However, if we have an animal that is extremely endangered, or if there is another specialist with an appropriate skill set that we don’t have, that’s when we reach out to our consultants.”
Calling on the Community
When a Grevy’s zebra showed signs of abdominal distress, Murray called Jennifer Brown, an equine specialist at a satellite hospital of the Virginia Tech veterinary school in Leesburg, Virginia. Brown decided she needed to operate in order to fix a twisted intestine, which can be fatal if not treated promptly. “It’s not common in zebras, but in horses it’s our most common emergency surgery,” says Brown. “Once they covered up the stripes, it was just like operating on a horse.”
Brown also performed surgery on a critically endangered dama gazelle to repair a tear in its vaginal wall, caused by a stillborn calf that was incorrectly positioned in the birth canal. Because the gazelle’s reproductive tract is very similar to that of horses and cows, Brown was a natural choice. Her skilled hand was essential to help ensure that the endangered gazelle will be able to conceive and deliver
a healthy calf in the future.
Sometimes an animal’s behavior dictates a certain approach. Such was the case when Zoo vets decided that some of the Zoo’s female orangutans should undergo tubal ligations in order to prevent pregnancies. These orangutans are Bornean-Sumatran hybrids, and the North American Orangutan Species Survival Plan designates that hybrids be placed on permanent contraception. Murray explains that it was important to go with a procedure that would avoid large incisions, because orangutans are very dexterous with their fingers and good at removing sutures. So she called in a veterinary laparoscopic surgeon, Clarence Rawlings, who performed the procedure via a thin tube inserted into two small incisions. He even added a few decoy sutures to reduce the chances that the apes would pick out the real ones. For good measure, keepers painted the ladies’ fingernails to give them something else to pick at.
|Painted fingernails and decoy sutures occupy an orangutan's attention while she heals from a surgical procedure. (Mehgan Murphy/NZP)|
One of the more frequent visitors to the zoo is veterinary dentist Barron Hall, who repairs and, when necessary, extracts teeth from everything from tiny golden lion tamarins to larger mammals such as tigers and gorillas. “A lot of it is endodontic [root canal] work, because we try to save the teeth if we can,” Hall says. Some animals, like elderly lioness Lusaka and female sloth bear Hana, have had as many as four root canals. Each species has its own challenges, Hall notes. “Apes have dentition very similar to ours, but with some of the bears and smaller animals, we don’t necessarily have dental charts and just have to wait until we get in there. Working on hoofed stock can be extremely difficult, especially in the back of the mouth, because they can’t open their mouths very far. Often we have to go through the outside to get to the roots of the teeth.”
The chance to help a variety of animals has led veterinary ophthalmologist Seth Koch to volunteer his time at the Zoo for 30 years. He has cared for everything from Sumatran tigers to giant pandas to, most recently, a milksnake. He once operated on a 50-plus-year-old crane with cataracts, enabling the bird to see again.
Another of Murray’s valued consultants is surgeon Kurt Newman, who refers her to a variety of specialists in the area; often, they are his colleagues at Children’s Hospital. “Pediatric doctors are used to having patients who can’t tell them what is going on, so that may give us a leg up in some of these cases,” Newman says. “With children we have to rely on the family, and at the Zoo we listen to keepers and the observations of staff.”
Newman remembers his surprise when Murray first called to seek his help with a tree kangaroo that had an infection of the face. “She was asking me about the location of the facial nerve, because they didn’t want to get into trouble when they operated,” he recalls. “I was thinking, ‘Oh my, how am I going to act smart here?’ Finding the facial nerve in a little baby is extremely difficult, and I wasn’t even sure what a tree kangaroo looks like.” Nevertheless, Newman offered to visit the Zoo and do what he could to help. “The night before,” he says, “I was talking to my son, who was then about eight, about this tree kangaroo, and he said, ‘Why don’t you just Google it?’ So we went online and found out that it lives in the forests of New Guinea and has a long face. So when I walked in there the next day, I was able to say, ‘Well, it has a long snout, so that nerve should be somewhere about here.’”
Picturing a Diagnosis
Just as in human medicine, sophisticated imaging technology has greatly improved the diagnosis and treatment of animal patients. National Zoo vets make use of portable digital imaging equipment donated by Fujifilm that allows them to take X-ray images that they can manipulate digitally afterwards—which is extremely helpful when dealing with large animals where you can’t always move them around to shoot multiple images.
|A tortoise gets an MRI (Jessica Siegal/NZP)|
Zoo vets also use ultrasound to monitor pregnancies and for routine diagnoses. But for more complicated procedures—such as investigating the lemur’s cardiovascular problem or performing an ultrasound-guided needle biopsy of a cheetah’s liver or an abdominal mass in an armadillo—they call on Cynthia Sloan, a radiologist at Southpaws Veterinary Clinic in Fairfax, Virginia.
When more extensive imaging is warranted, animals are sometimes transported to facilities outside the Zoo. At Southpaws, for example, Sloan has performed CT scans on a tortoise that could not move its limbs and a barium X-ray on a crane that could not swallow. Animals with suspected neurological problems—a golden lion tamarin with an abnormal gait, and a cheetah suspected of having pituitary gland tumors—have traveled to Iams Pet Imaging Center in Vienna, Virginia, which specializes in MRIs. All such scans are provided free of charge for the Zoo’s animals.
On several occasions, doctors have gone to great lengths to take specialized equipment directly to the Zoo’s patients. When a kidney stone blocked the ureter in an Asian small-clawed otter, Murray determined that surgery was not an option, because in otters a ureter that has been cut will constrict and close when it heals. She consulted Jason Engel, a urologist at George Washington University Hospital, who recommended shock wave lithotripsy. This procedure, which is also used with people, bombards kidney stones with sound waves and breaks them into tiny particles that can be passed in the urine. “I actually asked GW Hospital if I could bring the animal in there, but that wasn’t kosher,” Engel says. “So I arranged to truck in a mobile lithotripter owned by my group of doctors and asked a technician to volunteer to help. We set it up at the Zoo hospital, and the little animal was all ready, but when we took an X-ray to get the stone in the crosshairs of the machine, it turned out the otter had passed the stone.” Despite all the effort for naught, “afterward, everybody said they’d come back down in a heartbeat if we needed them,” Murray recalls.
Handling 'Wild' Patients
The outside specialists say that the greatest challenge of working with Zoo animals is that the patients must be anesthetized for any hands-on procedure, even diagnostic evaluations that would be routine on domestic animals. Nor can the doctors do much to relieve the animals’ stress. “You can’t pick them up and scratch them behind the ears or sit with them in recovery, petting them and talking to them as I do with my other patients,” says Julie Smith, medical director and chief of anesthesia at Iams Imaging.
“We always question the influence of stress and sedatives on our diagnostic data,” says veterinary cardiologist Steven Rosenthal of Chesapeake Veterinary Cardiology Associates, who has helped care for the Zoo’s animals for the past 12 years. “What in fact is normal is not necessarily established for these species. Also, within a species like dogs, there are different normals for different breeds, and we would expect the same is true in other species.” Specialists often have to rely on comparative medicine, he adds. “I know what’s normal in companion animals and what’s normal in people, so I have to make some leaps in what I perceive as normal in zoo animals.”
During any procedure involving zoo animals, efficiency is critical because anesthesia can be especially stressful. Zoo animals require constant monitoring to make sure they are sedated enough for safety, but not so deeply that their cardiovascular and nervous systems are dangerously depressed. With large animals, such as elephants, giraffes, or zebras, the sheer weight of lying on their side can compress muscles and nerves and cause damage. To minimize the risk of complications, vets try to limit the animals’ time under anesthesia to less than two hours.
The specialists all agree that treating Zoo animals keeps them on their toes, is a welcome change from their day-to-day routine, and is one of the most satisfying things they do. They treasure photos Murray sends them of their patients, signed by the Zoo’s veterinary staff. “They treat me like a rock star,” says radiologist Cynthia Sloan. “They don’t understand how much I love going out there. Their animal care is amazing, and the staff is so grateful, so kind and appreciative.”
|Dentist Barron Hall extracts the tooth of a spectacled bear. (Department of Animal Health/NZP)|
Some, like anesthesiologist Julie Smith and dentist Barron Hall, had previous experience working with zoos and are delighted with the opportunity to continue it here. Hall even chose to buy his current veterinary dentistry practice in Virginia because the previous owner had a long working relationship with the National Zoo.
The Zoo experience “has kept me thinking and inspired me to delve into areas that I otherwise wouldn’t have,” says cardiologist Rosenthal, who tracks the heart health of all the Zoo’s great apes in an effort to learn why captive male gorillas are especially prone to heart disease. “I think that has helped me as a clinician for the patients I routinely see.” Besides, adds Kurt Newman, “It all makes for very interesting conversations with my kids and at cocktail parties.”
—Phyllis McIntosh is a freelance writer who often covers medical topics and has published in numerous national magazines. She is also a volunteer interpreter at the National Zoo.
If you have a comment about Smithsonian Zoogoer magazine, please email it to us.ZooGoer 38(4) 2009. Copyright 2009 Friends of the National Zoo.