A sick 9-year-old mandrill is treated at the Biblical Zoo, Jerusalem, Dec. 2013.
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Mordechai I. Twersky
Sick monkey at the Jerusalem Biblical Zoo. Photo by Mordechai I. Twersky

Several months ago, staffers at the Jerusalem Biblical Zoo were befuddled. Doron, their colorful dominant-male mandrill, did not look good. Though he appeared to be eating normally, his weight had dropped precipitously. At 25 kilograms, he was about 20 kilos below the acceptable weight threshold for 9-year-olds like him.

“Clearly, something wasn’t right,” said Noa Danim, head keeper of the 70-year-old zoo’s primates section.

A thorough examination of Doron, including blood tests and a sonogram, pointed to type 2 diabetes, a metabolic condition that occurs when the pancreas can no longer produce enough insulin. “It was a severe case,” said Danim.

Instances of diabetes among primates are not unusual. A 2012 study by the Cleveland Metroparks Zoo in Cleveland, Ohio, found that zoo primates, “with their relatively high caloric density diets and sedentary lifestyles, may experience similar conditions that could predispose them to the development of diabetes.”

A team of veterinarians and zookeepers at the Jerusalem Biblical Zoo designed a daily treatment plan for Doron. With glucose meters in hand, staffers began testing his blood throughout each day, administering as many as eight insulin injections.

And they micro-managed his diet.

“Now we feed him a lot more vegetables, less fruit, and we have added protein,” explained assistant zookeeper Chagit Baduch. “A lot more leaves lettuce and a lot less of the monkey chow.”

A reporter was allowed to observe Baduch as she administered an insulin injection to Doron in an indoor protective chamber known as “the squeeze.” Iron bars separated Baduch from her patient, who remained awake and quiet. “The success of this treatment depends upon Doron’s cooperation,” said Baduch. “Receiving treatment and up to eight injections a day surely can’t be easy for him. But we try, wherever possible, to treat our mandrills when they are awake, and not under full anesthesia.”

With a morning regimen that begins at 8, Doron is fed and monitored indoors for three hours. His blood is tested again in the afternoon. Staff members attribute the primate’s readiness to submit to the daily medical grind to months of intensive preparation. “We train the mandrills to frequent the chamber in the event they, too, will require close observation and treatment,” said Baduch. “We feed them there. We interact with them there.”

Doron, who at the young age of six assumed the role of clan leader following the sudden death of his father, appears to be responding to the treatment, according to zoo officials. He is gaining weight, and his daily injections are down to three. Meanwhile, Doron’s new diet is already being prescribed for the entire clan of 14 mandrills, who are relatives of the baboon and one of the largest monkey species in the world.

The staff and Dr. Nili Avni-Magen, head veterinarian and zoological director, conduct early morning rounds to monitor the health of the mandrills, looking for the smallest of clues.

“Wild animals tend to hide symptoms, and it’s always a challenging diagnosis,” said Avni-Magen. “Thanks to the high level of training of Doron, with his dedicated keepers, we can treat him with his full cooperation.”

Zoo officials stress that before Doron is released each morning to the primates’ outdoor exhibition space, replete with downward stream, tree stumps and wooden monkey bars, he is always left in the company of at least six other mandrills.

“It’s like treating people,” explained Baduch. “We never leave them alone when they’re sick.”