Milwaukee County Zoo reveals unexpected death of Naku, female western lowland gorilla

MILWAUKEE -- The Milwaukee County Zoo announced on Monday, April 30 the unexpected death of female Western lowland gorilla, Naku.

Naku died on Saturday, April 28, zoo officials said in a news release. On Friday, zookeepers noticed Naku "appearing more tired than normal, but she was still responsive, and continued to eat and drink."

An examination revealed Naku was septic, and zookeepers learned the source of Naku’s illness was located in her abdomen, so an emergency surgery was then performed by a veterinary surgeon.

Surgery showed that Naku had a necrotic bowel, meaning a portion of the intestine had died, and was no longer functioning. Because of the location of the affected intestine, removal of the dead portion and re-attachment of the healthy sections was not a viable option. The animal care staff and veterinary team assessed that Naku would most likely have less than a 10 percent chance for survival with re-attachment surgery.  Rehabilitative care would have meant extended time under sedation for Naku, resulting in a poor quality of life.

The difficult decision was made that she be humanely euthanized. She was 17 years old.

Naku with Zahra

Naku is the mother of Zahra (shown above). Zahra is 8 months old -- and the most recent lowland gorilla birth at the zoo. Zahra was born on Sept. 9, 2017. Zookeepers estimate the baby most likely weighed about three pounds at birth.

Baby gorilla born at the Milwaukee County Zoo

Baby gorilla born at the Milwaukee County Zoo

Earlier this month, zoo officials announced the death of another Western lowland gorilla, Cassius -- a 31-year-old male. Cassius was Zahra's father, and he died on April 12. Officials said the exact cause of death was not known, but prior to his death, Cassius was not interested in food or water.

An exam revealed decreased liver and kidney function and that the heart may not have been contracting fully.

Cassius, 31-year-old gorilla, dies at the Milwaukee County Zoo

The remaining family group includes adult female, Shalia, youngster, Sulaiman and Zahra. This group, along with the zoo’s two adult male gorillas, make up the zoo’s troop.

Zoo officials noted in the release all of the gorillas are on antibiotics as a precautionary measure, since it’s too early to determine if Naku’s passing is related to Cassius.

At this time, it’s not known whether Naku’s necrotic bowel was caused by a viral, bacterial or environmental situation, zoo officials said. Staff is collecting environmental samples from the indoor Gorilla Exhibit for testing. The zoo is working with its pathology and laboratory partners for results of tissue and fluid cultures from both Naku and Cassius. Full necropsy results will be forthcoming and will help determine if there is a link between the cases.

Meanwhile, the well-being of the entire troop is being monitored. In the release, zoo officials noted that keepers have given Zahra visual access to both Shalia and Sulaiman, in the hope Shalia may eventually act as a “surrogate” mother.

Staff will continue to be with the family group 24 hours a day, seven days a week, and are skilled in the highly-sensitive situation this presents for Zahra -- losing both her mother and father.

Zoo officials said in the release after monitoring the family over the weekend, it was decided Zahra may be most successful with human-assisted rearing. Other zoo professionals that successfully navigated this difficult transition with other juvenile gorillas are assisting the zoo with this process, and providing valuable support and knowledge.

Zoo officials noted that Zahara was examined at the same time as her mother, and results showed no abnormalities. She's now being transitioned to baby formula, making sure that she’s receiving all of the nutrition she requires and monitoring her for any signs of illness.

The entire troop will be off exhibit indefinitely until Zahra is completely adapted to whatever situation is deemed best for her, zoo officials said.