Halver Lecture in Comparative Nutrition – Dr. Kathleen Sullivan

The 2023 Halver lecture in comparative nutrition, funded by late WSU alumnus Dr. John E. Halver III (1922-2012) and his family, featured Dr. Kathleen Sullivan, a comparative animal nutritionist who is an expert in mineral metabolism and a leading authority in black rhinoceros nutrition from the Animal Nutrition Center at Disney’s Animal Kingdom near Orlando, Florida. She has a PhD in nutritional biochemistry from the University of Florida, an MS in animal science and nutrition from North Carolina State University, and a BS in animal science from Cornell University.

More than 150 people attended Sullivan’s presentation, “Working Outside of Normal. Using Practical Nutrition Research for Exotic Animal Health: Comparative Mysteries.” Attendees learned that Disney is an accredited institution with the Association of Zoos and Aquariums and is part of a larger community that is leading initiatives to improve the standards of care across disciplines whose goals include the conservation of endangered species. The Disney animal nutrition team includes over 30 cast members and four working nutritionists. They work daily year-round to provide more than 800 diets for over 2000 animals.

“We have a mind for nutrition as preventive medicine,” said Sullivan who has been helping to care for and conserve animal species with Disney for the past 15 years. “We look at the impact of diet on health. We use what we know from our own experience with these species, as well as utilizing our colleagues in domestic industry and academia, to clinically assess and manage animals, balance diets, and optimize nutritional welfare.”

A white rhinoceros cow and her calf
A white rhinoceros cow and her calf. Courtesy Disney’s Animals, Science, and Environment

Nutrition impacts animal health and well-being, from susceptibility to illness and disease to reproduction. Sullivan’s presentation highlighted several challenging case studies where nutrition was used to solve problems in exotic animal species from stingrays to toads to rhinoceros.

In the first case study, Sullivan described a Southern white rhinoceros, Jao, who had not yet had a calf at 24 years old. Experts from multiple departments at Disney worked together to solve the problem. They looked at the rhino’s social interactions and behavior, measured her circulating reproductive hormones, reevaluated her diet, and compared her body weight to other female white rhinos who were reproductively successful. One of their approaches was to lower her elevated body weight, as she was larger than the adult male white rhinoceros at the facility. Much is known about the potential negative impact of obesity on fertility in women and across many animal species. The Disney researchers surmised the same may be true in rhinos and worked to better control Jao’s diet.

“We had to monitor her consumption,” said Sullivan. “Controlling her intake and getting over 400 pounds off her happened over seven years. But soon after it got there, we had a very welcome surprise – baby Mylo!”

Another case study involved the “toad who could not come to dinner.” Sullivan described the toads in question as lethargic and losing weight. The Disney team took blood from the toads and discovered that all of them had hypovitaminosis A, or low levels of vitamin A. Amphibians with vitamin A deficiency develop a condition called lingual squamous metaplasia or short tongue syndrome. The cells in the mouth and tongue of these animals do not produce the sticky mucous required to capture prey. This condition can be reversed if treated early. After a series of experiments to determine the most effective route and frequency of administration, the team discovered that a once weekly topical dose of vitamin A was most effective at preventing vitamin A deficiency.

Sullivan discussed Iron Overload Disorder, a condition that is common in black rhinoceroses under human care. Iron overload is caused by a chronic imbalance of iron metabolism in which iron accumulates and damages tissues and organs, leading to inflammation, infection, liver damage, skin lesions, and a shorter lifespan. Sullivan and the team at Disney’s Animal Kingdom evaluated the black rhinoceroses’ diet and determined that the pelleted feed typically fed under human care contained very high amounts of iron. To limit iron, they worked with Mazuri feeds to develop a low iron form of the high fiber low starch pelleted diet, removed alfalfa hay which had high bioavailable iron levels, and limited produce with high vitamin C, as the vitamin increases iron absorption. These dietary changes should help prevent iron overload. But how to treat the existing condition? Removing large volumes of blood by phlebotomy is commonly used to treat the similar condition in humans and can be used in black rhinoceroses. While Disney’s rhinos have been trained using positive reinforcement and voluntary participation as up to four liters of blood are removed, this process may not be practical at all black rhino holding institutions. Therefore, Sullivan and her team examined the effectiveness of an oral iron chelator called HBED on preventing iron accumulation. After determining that the synthetic chelator could be safely fed to horses, a model animal for rhinos because of their similar digestive system, the team fed it to the black rhinos. While the chelator removed iron, health complications that were resolved in one animal taught the team to be cautious and that chelation must be further studied. The black rhinos at Disney currently have healthy iron levels similar to wild rhinos in Africa thanks to diet and phlebotomy.

Sullivan’s last case showed applied use of the HBED chelator to successfully treat iron overload in dolphins. Due to a negative reaction to phlebotomy in the dolphins, who can carry loads of iron even higher than black rhinos, HBED was fed to promote iron binding and removal. When carefully monitored, HBED treatment decreased iron to levels equivalent in wild dolphins, improved liver size, and lowered inflammation. The treated dolphins displayed positive behavioral changes, including increased energy.

Sullivan wrapped up her presentation by saying, “Nutrition is awesome!” Understanding how nutrition impacts the body is critical to the health and welfare of our animals. Advice for students who might be interested in a career in comparative animal nutrition she said, “Never say no – always say YES to opportunities. Don’t be afraid to ask questions, as well as trying to make connections! Ask yourself what makes you happy. Is it a challenge?”