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Wednesday, March 15, 2017

Zoo vets perform surgery on lizard that weighs less than one pound

Posted by: Jeremy Dwyer-Lindgren, Communications
Photos by: Jeremy Dwyer-Lindgren, Woodland Park Zoo

Misho gets a pre-operation inspection from veterinary staff.

Say hello to Misho the chuckwalla, a member of our Woodland Park Zoo family since he arrived here in 2000.

Chuckwallas are lizards native to the southwestern US and northern Mexico, typically measuring a little over one foot in length. Like many plant-eating reptiles, they enjoy basking on rocks in the sun and eating leafy greens.

At 25 years old, Misho is certainly getting up there in age. And recently keepers noticed he hadn’t been feeling all that well.

Misho at the zoo's animal hospital. 

Reptiles like Misho certainly aren’t known for being the most emotive creatures, and he can’t exactly tell keepers what’s wrong. So how can keepers tell when a lizard isn’t feeling himself?

“It has to do a lot with posture and behavior,” explains Dr. Kelly Helmick, Woodland Park Zoo veterinarian. Healthy and happy chuckwallas spend a lot of time basking, raising themselves up off the rock a just bit. “If he’s flattened out on the rock—if he’s not basking and his color changes and he’s sitting there with his eyes closed—that’s what lethargy looks like in a lizard,” said Dr. Helmick.

Which was exactly what keepers noticed in Misho.

Our animal health team stepped in to give Misho a diagnostic exam: listening to the heart and lungs, taking blood samples, and feeling his abdomen. And that last test is when the vets felt something that should not have been there.

Radiographs soon confirmed what the vets could feel: Misho had grown himself a giant bladder stone.

“That’s a really big stone...in a very small lizard,” recalled Dr. Helmick after her first look at the radiograph.

Misho's radiograph. The stone can be seen clearly just above his tail, between his hind legs.

The stone, it would later turn out, weighed just shy of six grams and most likely took months to years to build up. For a critter that weighs in at a mere 220 grams (less than 1 pound), six grams is hardly a trivial addition: it accounted for nearly 3% of his entire body weight. To put that into human terms, the average US adult would have a four to five pound rock nestled conveniently inside their bladder.

“And that’s probably why Misho didn’t feel well,” said Dr. Helmick. “As the stone shifted around, it made him uncomfortable,” she said. The stone was clearly affecting his day to day quality of life, and it was clear it had to go.

Several weeks later,Misho is resting comfortably inside of a warm, roomy incubator in the animal health building, presurgical antibiotics, fluids, and analgesics administered, awaiting his now imminent surgery.

Anesthetizing lizards isn’t easy, and as the surgery gets underway, Misho isn’t proving to be an exception. They can go minutes without breathing, making it harder for the gas to take effect. That, plus our reptilian friend’s size also makes inserting a critical breathing tube challenging.

Misho is so small, in fact, that no one manufactures a breathing tube small enough to fit; vets on staff custom-make their own out of other materials for him and others his size.

Vets hold up Misho as they administer anesthesia.

“Everything about this surgery is miniature. Some of the things we need for surgery and anesthesia just aren’t made that small. So we adapt and make our own,” said Dr. Helmick.

After a tense stretch of thirty minutes, the customized tube settles in and the anesthesia begins to take full effect. Dr. Helmick makes an incision, and after a little bit of searching, finds the stone. Luckily it easily pops out, and Misho loses six grams.

“The stone was even larger than I expected,” said Dr. Helmick.

Dr. Kelly Helmick, left, stitches up Misho after removing his bladder stone.

Dr. Helmick finished the operation by carefully stitching Misho back up, a process she described as “careful, but quick.”

Misho recovered well enough that he was discharged the next day back to his behind-the-scenes home, temporarily relocated from the Day Exhibit after the December 2016 fire. One thing remains a reassuring constant for Misho: rejoining his 16-year-old daughter and companion, Dembi.

As Misho continues to recover in the coming weeks, keepers and vet staff will keep a close eye on him to make sure he’s feeling well.

For Dr. Helmick, the surgery is part of another day on the job. “It’s part of the fun of a being a zoo veterinarian,” she said. “We provide the best care for our patients regardless of their size.”

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