PHOTO: Test reveals why female lion in Oklahoma zoo sprouted a mane

These photos provided by the Oklahoma City Zoo taken March 25, 2017, left, and Nov. 23, 2017, right, show Bridget, a lioness that has grown a mane.
These photos provided by the Oklahoma City Zoo taken March 25, 2017, left, and Nov. 23, 2017, right, show Bridget, a lioness that has grown a mane.

OKLAHOMA CITY — Lab results have revealed the answer to a mystery at an Oklahoma zoo about what caused a female lion to sprout a mane.

The Oklahoma City Zoo said in its March newsletter that testing at the University of Tennessee found the African lioness named Bridget has an elevated level of androstenedione, a hormone that can contribute to developing male features.

Veterinarians compared Bridget's blood to samples from her sister, who has no mane. Bridget's blood also contained a higher level of cortisol, which regulates metabolism and the immune system.

The zoo said the results likely mean the 18-year-old lioness has a benign tumor that's producing the hormones, but that her health is excellent.

The zoo said female lions with manes are not unheard of, but they are rare.

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