During the height of the Covid-19 pandemic, Dr. Lily Parkinson, an emergency and critical care veterinarian at the University of Georgia, received urgent calls regarding snow leopards. The coronavirus had spread to various zoo animals, but snow leopards were particularly susceptible to severe illness, often developing anemia—a dangerous lack of red blood cells that starves the body of oxygen. For human patients, or even household pets, such a condition would typically be treated with a straightforward red blood cell transfusion from a readily available blood bank.
However, blood banks for exotic animals like snow leopards simply didn’t exist. Furthermore, knowledge about blood types and compatibility in these wild species was severely limited. Zoos across the country desperately sought compatible donors. Some institutions with healthy snow leopards were willing to sedate their animals, collect blood, and send it to Dr. Parkinson, who, by coincidence, was already researching blood types in large wild cats. The logistical hurdles were immense, often proving impossible to overcome. Staff shortages due to illness meant fewer hands to collect blood. Precious samples were sometimes lost in transit. Dr. Parkinson recounted how even zoos eager to contribute found it impossible to disrupt their existing operations to facilitate donations. Tragically, some leopards succumbed to their rapidly worsening conditions and had to be euthanized before a transfusion could even be arranged.
Now at Brookfield Zoo Chicago, Dr. Parkinson is spearheading an ambitious project: creating a pioneering blood bank specifically for zoos and aquariums. This vital resource would store pre-screened blood from a diverse range of exotic animals, a lifeline that could have saved those snow leopards and countless others. To achieve this, she’s adapting advanced human medicine techniques that enable red blood cells to be cryopreserved—frozen on ice for many years. Successfully applying this to species like polar bears, pangolins, dolphins, and dik-diks would revolutionize emergency animal care. Her vision is to “theoretically try to bank every animal that we have in zoos and have it frozen and ready.”
Understanding the Challenge: A Short Shelf Life
The project involves careful work, like that performed by Dr. Parkinson, assisting with blood draws and exams. Here, River, a clouded leopard, undergoes a procedure, with veterinary student Sylvia Kimmel from Cornell also assisting. Blood, in both humans and animals, comprises various elements, including red blood cells, responsible for oxygen transport, and plasma, the fluid carrying these cells. While many zoos already collect and store plasma—which freezes easily and is rich in nutrients and antibodies—to treat animals like newborn giraffes lacking maternal antibodies. However, animals battling severe infections, chronic illnesses, or significant blood loss often require transfusions of red blood cells. The main obstacle is that these delicate cells are prone to rupture during conventional freezing and thawing processes.
In human medicine, red blood cells can be frozen for rare blood types or for use in combat zones, preserving them for a decade or more. However, this method is intricate, costly, and demanding. Standard human blood banks, with their rapid turnover, typically refrigerate red blood cells for only about six weeks. Dr. Parkinson explains that this short shelf life is simply “not practical for zoos.” Animal transfusions are infrequent in zoos, and red blood cell characteristics differ vastly across species. Dr. Parkinson points out that “Every animal seems to have its own unique type of red blood cell, and then many different types of blood types as well.” Maintaining a refrigerated blood bank would mean constantly collecting blood from numerous species, with most of it likely going unused and wasted.
A blood bag holds a sample drawn from River, the clouded leopard, a crucial step in the cryopreservation process. Dr. Parkinson works diligently to collect blood samples, strategically coinciding with routine wellness exams for the zoo’s animals. After collection, Dr. Parkinson meticulously labels the blood bags containing River’s samples, preparing them for freezing. Last year, Dr. Parkinson secured a grant from the American Association of Zoo Veterinarians to research the viability of freezing red blood cells from diverse exotic species.
Dr. Taylor Yaw, Vice President of Science and Animal Health at the Henry Doorly Zoo and Aquarium in Omaha (which contributes elephant blood to the project), noted that this is “a technology that’s in human medicine but really kind of forward-thinking in terms of veterinary medicine.” The core question is, “Can we freeze these red blood cells, cryopreserve them, and then basically wake them up at a future date?”
The Deep Freeze: Pioneering Cryopreservation for Wildlife
With funding secured, Dr. Parkinson’s primary goal is to “collect as much blood as I can,” often coordinating with routine wellness exams at Brookfield Zoo Chicago. For instance, during a recent Friday morning, River, an 8-year-old clouded leopard, underwent a full checkup. After sedation, the veterinary team performed a thorough examination, including dental work, a CT scan, and an ultrasound. Following these procedures, approximately a quarter cup of her blood was collected and handed over to Dr. Parkinson. Dr. Parkinson then used a centrifuge to separate the red blood cells from River’s plasma. A glycerol solution was carefully added to safeguard the cells during the freezing process. The sample joined an expanding collection in a specialized freezer, already containing red blood cells from diverse species like gorillas, bottlenose dolphins, orangutans, a polar bear, an emu, and a pangolin.
Dr. Parkinson closely monitors River during her CT scan. From an adjacent room, the team carefully monitors River during her diagnostic scan. A captivating glimpse of River’s beating heart during the examination. Merely collecting these varied samples has been a significant undertaking, demanding both patience and innovative solutions. For smaller donors, such as koalas, pangolins, and the cat-sized African dik-diks, Dr. Parkinson had to specially assemble tiny 20-ml blood bags—which she affectionately described as “adorable.” Samples are also arriving from partner institutions: beluga whale blood from Chicago’s Shedd Aquarium, elephant blood from Omaha’s Henry Doorly Zoo and Aquarium, and giraffe blood from the Cheyenne Mountain Zoo in Colorado Springs.
The Cheyenne Mountain Zoo, a key collaborator, had already been instrumental in setting up a national plasma bank for giraffes. They achieved this by training some of their animals to voluntarily participate in blood draws, eliminating the need for sedation. Amy Schilz, a senior animal behaviorist at the zoo’s giraffe center, proudly states, “We’ve got giraffes that will stay for upward of 20 minutes and allow us to draw plasma.” As a reward for their cooperation, these giraffes receive rye-crisp crackers, which Schilz likened to “giving them a candy bar.” Having previously assisted Dr. Parkinson with a giraffe plasma study, Ms. Schilz eagerly supported the expansion of her research to include red blood cells, declaring, “I’m all in. Just tell me what you need, and we’re going to go get it.”
Various animal blood samples are meticulously stored within the specialized freezer. The video highlights Dr. Parkinson’s collaborative efforts, showcasing samples like beluga whale blood from Shedd Aquarium, elephant blood from Henry Doorly Zoo, and giraffe blood from Cheyenne Mountain Zoo. A cryopreserved bag of dolphin blood, a testament to the bank’s diverse collection.
The Great Thaw: Testing Viability
The true test will unfold after the samples have been frozen for six months. Dr. Parkinson will then carefully thaw each one, meticulously washing away the glycerol solution. As she humorously describes it, the goal is to “compare it to how happy it was before I froze it,” evaluating its condition post-thaw. Her assessment will include examining how many cells survived intact, their appearance under a microscope, and their metabolic activity. A key factor will also be whether the cells can endure automated washing—a more efficient method—or if they require the significantly more labor-intensive process of manual handling.
Initial findings are encouraging: red blood cells from giraffes and elephants “appear to mind being frozen” very little, according to Dr. Parkinson. This breakthrough holds particularly exciting potential for elephants, a species susceptible to a virus that can cause life-threatening internal bleeding. Cryopreservation could enable zoos to store blood from elephant calves, allowing for self-transfusions if they become ill later in life. Dr. Parkinson envisions a future where “They could donate their own blood to themselves.”
The project initially focused on giraffes at Brookfield Zoo Chicago. Their red blood cells successfully endured freezing, offering a promising indication that this cryopreservation method could be applied to a wide array of species. While River recovered from sedation, another clouded leopard in an adjacent enclosure rested peacefully. A giraffe at Brookfield Zoo Chicago observes visitors. Some zoos have successfully trained animals for voluntary blood draws, eliminating the need for sedation. However, early tests with polar bear and emu blood have not shown the same promise. Dr. Parkinson notes these were small samples and that adjustments to the thawing protocol might yield better results.
This research is still in its nascent stages, but Dr. Parkinson holds a strong vision for the future. She hopes that critically ill lions, lemurs, or leopards in zoos will one day receive care without veterinary teams having to frantically search for suitable blood. “You can just focus on the ill animal,” she emphasizes, “and then maybe we can have a central blood bank that worries about all the other stuff for you.”