News and Stories

For three decades, the Imperiled Cat Signature Project at Cincinnati Zoo’s Center for Conservation and Research of Endangered Wildlife (CREW) has advanced the conservation of small wild cats through assisted reproductive technologies. In recent years, that expertise has expanded to several big cat species, including the African lion. Dr. Julie Barnes, a veterinarian and researcher with the Imperiled Cat Signature Project, serves as Reproductive Advisor for the Lion Species Survival Plan (SSP). The SSP is a partnership among AZA-accredited zoos that coordinates breeding and population management to help ensure the long-term health and genetic diversity of African lions in human care.

To support this work, Dr. Barnes completed rigorous specialty training in theriogenology, the veterinary specialty focused on animal reproduction. In 2025, she became the first veterinarian at an AZA-accredited institution to earn board certification in theriogenology. Today, she works with zoos across North America to diagnose fertility challenges, develop reproductive management strategies, and apply assisted reproductive technologies to support African lion conservation.

Dr. Barnes is already applying these advanced reproductive techniques to some of the most challenging fertility cases in African lions. One collaboration focused on two female lions that had not produced cubs despite being paired for breeding.

One female would not accept natural breeding, so the team attempted artificial insemination over two consecutive breeding seasons, carefully timing the procedures to coincide with her natural reproductive cycle. Although pregnancy was not achieved, the work continued during a planned preventive spay, when the Imperiled Cat Signature Project performed a successful gamete rescue. Eggs collected from her ovaries were fertilized through in vitro fertilization (IVF), resulting in four embryos that are now cryopreserved for future breeding efforts.

Another female lion that had not conceived despite repeated natural breeding was enrolled in CREW’s natural reproductive cycle monitoring study. Dr. Barnes and the CREW team are evaluating a combination of fecal hormone metabolites, blood and salivary hormones, vaginal cytology, reproductive behaviors, and vocalizations to identify new, real-time indicators of estrus that could improve the timing and success of future artificial insemination procedures.

Beyond individual fertility cases, Dr. Barnes is helping develop a novel, multimodal approach to evaluating reproductive health in females. Because no standardized approach currently exists to evaluate reproductive health in cats, many fertility problems go undetected until breeding has failed or advanced disease has developed. The CREW team is collecting data across the Lion SSP to establish reproductive health benchmarks, identify causes of infertility, and evaluate how contraception influences long-term reproductive health. Each evaluation integrates ultrasound, endoscopy, hormone monitoring, microbiome analysis, and microscopic tissue evaluation into one comprehensive assessment of female reproductive health. Although this work is currently focused on African lions, jaguars, and Amur leopards, the diagnostic tools and reproductive health benchmarks developed through these studies have the potential to transform reproductive medicine for wild cats worldwide.

Reproductive evaluations are equally important for male lions. Each examination not only helps assess a lion’s fertility but also provides an opportunity to preserve his genetics for the future. Since 2023, Dr. Barnes and the CREW team have performed comprehensive reproductive evaluations and semen collections on seven genetically valuable male African lions. Semen from each male is cryopreserved in CREW’s CryoBioBank, preserving irreplaceable genetics that can support future breeding efforts for decades to come. As new samples are added, the Imperiled Cat Signature Project continues to refine semen freezing techniques to improve sperm survival after thawing, increasing the value of every sample stored. Together, these advances are providing conservationists with powerful new tools to preserve genetic diversity, strengthen the long-term sustainability of African lions, and advance reproductive conservation for wild cats worldwide.