Patricia Yollin, Chronicle Staff Writer
Wednesday, August 24, 2005
A desert tortoise named Cactus has traded in four bladder stones for a fiberglass underbelly.
The reptile returned to public display this week after undergoing an unusual operation in which the zoo's head vet, Dr. Freeland Dunker, had to cut into his shell.
"We faced a unique challenge," Dunker said Tuesday. "In a mammal, bird or anything else without a shell, this would be fairly routine surgery."
One stone was the size of a baseball and the other three were as big as golf balls. They added up to 553 grams, a little over a pound -- which is a lot for an animal like Cactus, who normally weighs 8 pounds and enjoys eating his namesake.
Dunker discovered the stones in 1994 and has monitored them over the years. When Cactus reached a hefty 10 pounds in the past month -- a career high -- the vet took X-rays and decided the growing stones needed to be removed.
"Cactus was slow and not very responsive so we knew something was going on," said Joe Fitting, director of the zoo's Animal Resource Center. "He wasn't his perky little self."
Bladder stones occur frequently in both captive and wild tortoises, and can be life-threatening when they get to be as gargantuan as the one Cactus had.
"When people don't urinate enough they tend to develop bladder stones," Fitting said. "Desert tortoises don't urinate enough. They want to retain water. They're desert specialists."
During last week's 90-minute operation on Cactus, Dunker cut a 3-by-4- inch rectangle in the tortoise's plastron, or underbelly shell, partially scoring the flap closest to the head.
"I hinged it and left it up like the hood of a car," Dunker said. "Then we had our starting point."
After removing the stones, he applied a fiberglass patch and sealed it with five-minute epoxy. It will take two years to heal.
"It was like fixing a ding in a surfboard," said Dunker, who performed a similar operation in 1992 on a tortoise from San Francisco's Randall Museum.
On Monday, Cactus was out of the hospital and back on the floor in the Herpetology Room of the Animal Resource Center, living amid hay and grasses. Desert tortoises Mojave and Helga also occupy the space, in separate but equal enclosures.
As a member of the zoo's educational outreach program, Cactus is a well- traveled reptile. He goes to classrooms, senior citizen centers, community events and wildlife theater shows.
"He's been seen by millions of people in the 20 years he's been doing education," Fitting said.
He added that Cactus arrived at the zoo in 1985 after living with someone in Napa for five years. It's not clear who his first owner was or if he was taken from the wild.
While he's recuperating, Cactus has been eating his favorite salad -- endive, bok choy and dandelion greens topped with geraniums and beets.
The surgery hasn't seemed to faze him.
"He came around within 24 hours. He's a mellow little guy," said Fitting, a fan of all desert tortoises.
"These are really very wonderful animals," he said. "They're very gentle and curious, and orange and red are their favorite colors -- in the wild their best and most succulent food is the red and yellow flowers on cactus."
Desert tortoises are also extremely imperturbable.
"You know the tale of the hare and the tortoise?" Fitting said. "These guys don't consider themselves in the race. They couldn't care less. They've been around 200 million years. They've seen dinosaurs come and go, and they're one of the reptile lines that survived the wipeout 65 million years ago. They're very laid-back."
The desert tortoise -- the state reptile of California -- is found in the Mojave and Sonoran deserts as well as parts of the Southwest and Mexico. Its population has declined 90 percent since the 1980s, Fitting said, and it was listed in 1989 as threatened under the California Endangered Species Act.
Predators, habitat destruction and illegal collection for the pet trade are all problems, and their enemies range from crows and coyotes to miners, cattlemen, off-road vehicles and the military.
In captivity, the reptile's life span is 80 to 100 years.
"They get three square meals," Fitting said. "And they have a better medical plan than you or I do."
And that's a good thing, given that desert tortoises everywhere are prone to bladder stones.
"Tortoises, being a desert animal, use their bladders as a canteen for water exchange," Dunker said. "They recirculate it through their bladder. This urine can get stagnant, especially after drought or hibernation."
He said that wild tortoises will urinate as a defense when they're picked up and often die as a result, after losing all their water. For a tortoise, a full bladder is as basic as food.
Fitting said the three tortoises at the zoo urinate only about once a week.
The fiberglass cover that Cactus has received functions much as a Band- Aid. If it cracks during the two-year healing period, Dunker will reinforce it.
And it will be with Cactus for the rest of his life, just like the one that fellow zoo resident Helga received years ago after her shell was sliced open to deal with another byproduct of tortoise anatomy: Her eggs were blocked and rotting inside her body.
"Now she's shiny underneath," Dunker said. "But you really don't see it unless you pick her up."
E-mail Patricia Yollin firstname.lastname@example.org.