Scientists at the Smithsonian Conservation Biology Institute say a study of 34 cheetahs at eight institutions found that while the hormones and eggs of cheetahs older than 8 years appear normal, the animals' uterine tracts tend to suffer from abnormal cell growth, infections and cysts that prevent pregnancy.
"Those of us who work with cheetahs have anecdotally noted that it's hard to reproduce older cheetahs, but this is the first time anyone has documented how aging affects the physiology of reproduction in this species," SCBI biologist Adrienne Crosier said.
About 80 percent of adult female cheetahs in North American institutions have never reproduced, the study said.
"We were relieved to find that, unlike in other older mammals, the eggs in older cheetahs can produce viable-appearing and growing embryos, which means we may be able to transfer them to younger cheetahs and preserve genetic diversity."
SCBI researchers said an attempt to extract eggs from a cheetah older than 8 years that has not reproduced and to fertilize the eggs and transfer them to a younger female could be made within the next two years.