CLEVELAND -- Officials with the Cleveland MetroparksZoo say a pregnant Grant's zebra and her unborn foal were found dead in their night quarters by animal keepers early July 4.

Nettie, the 7-year-old zebra, was pregnant with her second offspring and zoo officials say she appears to have died overnight during the birthing process.

An animal autopsy will be performed to determine the cause of death.

Nettie was born at the Cleveland Zoo in May 2005 and was mother to a female foal born at the zoo in September 2010. The two shared their exhibit in the zoo's African Savanna with slender-horned gazelles.

According to zoo officials, Grant's zebras are native to Ethiopia, Somalia and northern South Africa. They have an average lifespan of 20-30 years.