At the Toledo Zoo in Ohio, handlers administer a daily dose of Prozac to Johari, an adult female gorilla, to keep her calm.
The nervous ape was first put on the medication in 2002 after being introduced into a new breeding group. She would often throw screaming fits and attack her sister.
The emotional outbursts occurred around the same time as Johari's menstrual cycle, almost like PMS syndrome in women, explained Toledo Zoo veterinarian Wynona Shellabarger.
Consultation with other institutions and human physicians led zoo doctors to try antianxiety medication.
"We feel it really has helped her," Shellabarger said, adding that there have been no adverse side effects.
"Over the course of the last couple of years, she's bred, produced two offspring, and has been raising her second baby very nicely. And she seems well integrated into the group."
Things were going so well that Johari was taken off the medication for a month. But her premenstrual tension proved too much and she started to slip back to her old ways. She now remains on a daily dose.
When Misty, a polar bear at the Calgary Zoo in Canada, started to pace uncontrollably in her enclosure, she was given Prozac.
"Polar bears are notorious for pacing," explained zoo veterinarian Doug Whiteside. "They wander in the wild for long distances and probably have this internal drive to walk, and zoos can't provide them with the huge distance."
Whiteside said Misty significantly reduced her pacing when she was given the drug in 1995. She only had to stay on it for five months to cure the disorder.
But according to Whiteside, the majority of zoos don't use drugs. Instead the facilities rely on environmental and behavioral enrichment to prevent obsessive-compulsive disorders, like pacing, from developing.
For example, branches and boulders are occasionally moved around to make the enclosures look new to the animals. Handlers also present animals with mental challenges, such as placing food inside PVC piping and allowing the animals to figure out how to reach it.
Within the last five or six years zoos have focused heavily on designing enclosures that meet animals' mental and physical needs, Whiteside said.
Steve Marsden, a veterinarian and naturopathic physician, is an advisory board member for the Veterinary Institute of Integrative Medicine in Arvada, Colorado.
Marsden says antidepressants should only be used as a last resort for animals. He believes a simple change in diet can help with problems such as separation anxiety, fear-related aggression, and dominance-related aggression.
"The ideal diet that seems to be a unifying theme in managing most cases, regardless of diagnosis, seems to be an increase in protein and/or fat, and a decrease in carbohydrate content of the diet," he said.
But no studies have proven that a change in diet works for animal behavioral problems, he said. The belief is based purely on anecdotal experience.
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