During the peak of the Covid-19 pandemic, Dr. Lily Parkinson, an emergency and critical care veterinarian at the University of Georgia, found herself facing an urgent new challenge: sick snow leopards. The coronavirus had spread to various zoo animals, but these majestic big cats were particularly vulnerable, often developing severe anemia – a critical shortage of oxygen-carrying red blood cells.
For human patients, or even household pets, such a condition would typically be treatable with a routine blood transfusion from an established blood bank. But for snow leopards, such a resource simply didn’t exist.
The lack of a dedicated blood bank for exotic animals meant veterinarians had limited knowledge of their unique blood types and compatibility requirements. Zoos rushed to find suitable donors, with healthy snow leopards being sedated and their blood sent to Dr. Parkinson, who, by coincidence, was already researching blood types in large wild cat species.
However, the logistical hurdles were immense, often proving insurmountable. Many essential zoo staff members were ill, and precious blood samples were lost in transit. Dr. Parkinson recounted, “Other zoos that really wanted to donate and help were just not able to drop everything that they already had on their schedule.”
Tragically, some leopards succumbed to their illnesses so rapidly that transfusions couldn’t be arranged in time, leading to euthanasia.
Now, as a clinical veterinarian at Brookfield Zoo Chicago, Dr. Parkinson is pioneering a groundbreaking initiative: establishing the first-ever blood bank for zoos and aquariums. This vital resource will house prescreened blood from a diverse range of exotic animals, offering a lifeline during future health crises.
Her innovative approach adapts cryopreservation techniques from human medicine, which allow fragile red blood cells to be preserved for years. If successful for species like polar bears, pangolins, dolphins, and even tiny dik-diks, this could revolutionize emergency veterinary care. Dr. Parkinson envisions a future where “we could theoretically try to bank every animal that we have in zoos and have it frozen and ready.”
The Challenge of a Short Shelf Life
Dr. Parkinson oversees River, a clouded leopard, during a comprehensive wellness exam and blood draw, assisted by veterinary student Sylvia Kimmel from Cornell.
Blood, in both humans and animals, comprises various elements, including oxygen-carrying red blood cells and plasma, the fluid in which they float. While zoos already store plasma—easily frozen and rich in nutrients and antibodies—for common treatments like aiding newborn giraffes, red blood cells pose a unique challenge.
Animals battling infections, chronic illnesses, or severe blood loss often require red blood cell transfusions. Unfortunately, these delicate cells are prone to damage and rupture during the freezing and thawing process.
Though human medicine sometimes freezes red blood cells for rare types or military use, the process is costly and demanding, preserving cells for over a decade. Standard human blood banks prefer refrigeration, which offers a six-week shelf life. Dr. Parkinson explains that this short window “just doesn’t fit the timeline of what you need in a zoo,” where demand is unpredictable.
Animal transfusions are infrequent, and red blood cells differ wildly across species. Dr. Parkinson notes, “Every animal seems to have its own unique type of red blood cell, and then many different types of blood types as well.” A traditional refrigerated blood bank would mean constant collection from countless species, with most of the precious donations going to waste.
A close-up of a blood bag, carefully filled with a sample drawn from River, the clouded leopard.
Dr. Parkinson strategically collects as many blood samples as possible, integrating the process with the animals’ routine wellness examinations at the zoo.
Dr. Parkinson meticulously labels collection bags filled with River’s blood samples, preparing them for cryopreservation.
Last year, Dr. Parkinson secured a grant from the American Association of Zoo Veterinarians to explore the viability of freezing red blood cells from various exotic species.
“This is a technology common in human medicine, but truly groundbreaking for veterinary applications,” remarked Dr. Taylor Yaw, Vice President of Science and Animal Health at the Henry Doorly Zoo and Aquarium in Omaha, which is contributing elephant blood to the study. “The question is, can we successfully cryopreserve these red blood cells and then effectively ‘reawaken’ them later?”
The Deep Freeze: Preserving Precious Samples
With dedicated funding secured, Dr. Parkinson is now focused on “collecting as much blood as I can.” She skillfully integrates blood collection into the routine wellness exams at Brookfield Zoo Chicago. For instance, during a recent Friday morning checkup for River, an 8-year-old clouded leopard, the veterinary team performed a full examination, including a dental check, CT scan, and ultrasound, before carefully drawing about a quarter cup of blood for Dr. Parkinson’s research.
After processing River’s blood in a centrifuge to separate the red blood cells from the plasma, Dr. Parkinson carefully added a glycerol solution—a crucial step to protect the cells during freezing. The sample then joined a burgeoning collection in the freezer, which already contains red blood cells from diverse species such as gorillas, bottlenose dolphins, orangutans, a polar bear, an emu, and a pangolin.
Dr. Parkinson meticulously monitors River, the clouded leopard, during her CT scan.
From a separate control room, the veterinary staff closely monitors River’s CT scan, ensuring her safety and well-being.
A captivating image of River’s strong, beating heart captured during the CT scan.
Collecting these varied samples has been an impressive undertaking, demanding both patience and innovative solutions. For the smaller donors, such as koalas, pangolins, and dik-diks (a small, cat-sized African antelope), Dr. Parkinson had to specially adapt tiny 20-ml blood bags, which she affectionately calls “adorable.”
In addition to samples from Brookfield Zoo, Dr. Parkinson is collaborating with other leading institutions, receiving beluga whale blood from the Shedd Aquarium in Chicago, elephant blood from the Henry Doorly Zoo and Aquarium in Omaha, and giraffe blood from the Cheyenne Mountain Zoo in Colorado Springs.
The Cheyenne Mountain Zoo, a pioneer in establishing a national plasma bank for giraffes, has already successfully trained some of its animals to voluntarily cooperate with blood draws, eliminating the need for sedation.
Amy Schilz, a senior animal behaviorist at the Cheyenne Mountain 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 delightful reward for their cooperation, these towering donors receive rye-crisp crackers, which Ms. Schilz likens to “giving them a candy bar.”
Having previously collaborated with Dr. Parkinson on a giraffe plasma study, Ms. Schilz was enthusiastic about extending her support to the red blood cell research, stating, “I’m all in. Just tell me what you need, and we’re going to go get it.”
A collection of meticulously organized animal blood samples nestled in the cryogenic freezer.
Dr. Parkinson’s collaborative efforts extend to other prominent institutions, sourcing beluga whale blood from Chicago’s Shedd Aquarium, elephant blood from Omaha’s Henry Doorly Zoo, and giraffe blood from Colorado Springs’ Cheyenne Mountain Zoo.
A single frozen bag containing precious dolphin blood, carefully preserved for future use.
The Great Thaw: Testing Viability
The ultimate test awaits after these cells have endured six months in cryogenic storage. Dr. Parkinson will then meticulously thaw each sample, carefully removing the protective glycerol solution. Her goal, she explains, is to “compare it to how happy it was before I froze it,” assessing its viability.
Her evaluation will involve a comprehensive analysis: counting intact cell survival, microscopic examination for normalcy, and metabolic activity, among other crucial indicators. Additionally, she will determine if the cells can withstand automated washing processes or require the more time-consuming manual handling.
Promising early findings indicate that red blood cells from giraffes and elephants “appear to mind being frozen” remarkably well, according to Dr. Parkinson.
This breakthrough holds particularly exciting implications for elephants, a species susceptible to a virus causing fatal internal bleeding. Cryopreservation could enable zoos to store blood from elephant calves, allowing for autologous transfusions—meaning, “They could donate their own blood to themselves,” as Dr. Parkinson explains.
Giraffes at Brookfield Zoo Chicago. The success of freezing giraffe red blood cells early in the project provided crucial evidence that this cryopreservation method could be adaptable for various species.
A peaceful moment: another clouded leopard rests in its enclosure as River recovers from her recent examination and sedation.
A towering giraffe at Brookfield Zoo Chicago observes visitors below. Some forward-thinking zoos have already trained their animals for voluntary blood draws, eliminating the need for sedation.
However, initial results for polar bear and emu blood were less encouraging, Dr. Parkinson revealed. She noted that these were small samples, and further adjustments to the thawing protocol might be necessary.
While still in its preliminary stages, Dr. Parkinson’s research holds immense promise. Her ultimate vision is a future where zoos with critically ill animals – be they lions, lemurs, or leopards – can dedicate their full attention to patient care, freed from the urgent, often impossible task of finding exotic animal 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.”