Ivy the leopard, being prepped in another room, also needed medical treatment for her limp. The zoo's 68-pound black cat, which had arthroscopic surgery in 2009, was showing signs of pain again in her elbows.
The zoo staff was worried.
"I imagine we are going to end up euthanizing her at some point if it can't be fixed," said Beth Schaefer, the zoo's curator of carnivores and primates.
With two big cats needing attention, surgeon Brian Beale of Gulf Coast Veterinary Specialists and stem-cell specialists at InGeneron Inc. donated their services to treat the animals. While Beale removed bone chips and cleaned the joints during arthroscopic surgery, InGeneron staffers produced stem cells from each animal's body fat.
When the surgeries were complete, Beale injected the stem cells, which had taken about two hours to process for each big cat, into the animals' joints to promote faster healing.
Pandu, always a big baby looking for attention, was moving a bit slowly the day after surgery.
Feisty Ivy pretended nothing was wrong.
A week after the surgery, Houston Zoo veterinarian Lauren Howard says neither animal has suffered complications. Pandu, with mild swelling, was released into his exhibit half-days on Monday.
Ivy returned to her exhibit Saturday. Specialists expect to see an improvement in her gait within two to three weeks.
During the surgery, Pandu earned an extra dose of sympathy when his joint damage and bone chips appeared on the surgeon's monitor. Zoo staffers were amazed the cat hadn't been showing more lameness.
"They were the largest fragments that I have ever found in at least 15 years," said Beale, who does the arthroscopic procedure mostly on dogs. "We had to break the fragments down into pieces because our instruments weren't big enough to haul that piece out," he said.
The zoo employees who had been scurrying around Pandu doing the surgery prep as he lay sprawled out on the table were silent when Beale went to work on the cat. Tension broke in the room as the surgeon began describing what he was doing to spectators watching the monitor.
When it became clear that Pandu's biggest bone chip wasn't going to be dislodged easily, Beale asked for a mallet to break up the fragment. That was when trainer Samantha Junker's gulp of alarm got some chuckles from her colleagues, who reassured her Pandu would be OK.
The zoo-born tiger, bred as part of a species survival program, has lived in Houston since he was 6 months old. The 13-year-old cat started limping occasionally about six months ago, Schaefer said.
Tests showed a problem with Pandu's joint that was beyond the expertise of the zoo's veterinary staff, which mostly deals with preventive medicine and wound maintenance. The veterinarians called Gulf Coast, which often provides diagnoses or treatment help.
Ivy's elbow joints always have been a worry for the carnivore staff.
The black leopard has had a tough life. She was among about 50 young tigers and leopards seized by California authorities in 2003 from an illegal breeder.
Ivy was nursed back to health and sent to the Houston Zoo in 2008 along with fellow rescue Kadu, who had been declawed by breeders.
While Kadu is bigger and healthy, Ivy arrived at the zoo with mobility problems. Kevin Hodge, Ivy's trainer, said it was hard to know the source of her medical issues, which could be due to inbreeding, a poor diet early in life or living in an inadequate cage during her formative years.
After surgery, Beale said he found similar joint problems in both animals, who were missing cartilage and had bone painfully grinding on bone. He hopes the stem-cell therapy will help the problem. Stem cells are a primitive form of cells that change into other kinds of cells based on where you inject them, Beale said.
"So inside the joint, we hope that they will turn into cartilage cells and produce new cartilage," Beale said. "The stem cells also seem to play a role in decreasing the inflammation of the joint and helping to prevent the joint from becoming as stiff."
In the fall, InGeneron did a similar stem-cell procedure with the zoo's babirusa, a species of Asian pig, that provided some improvement in the babirusa's mobility. The company also successfully used the stem-cell treatment on a tiger in Mexico with a hip injured during a tropical storm, said Carl Friddle, vice president of the Houston company.
Although her prognosis is not as good as Pandu's, there is good news for Ivy, Beale said. If this treatment doesn't give her relief, the leopard could be a candidate for an artificial joint.
"Elbow replacements are done with dogs right now. It is something that is new," Beale said. "It is amazing how we do the same things in dogs and cats that we do in humans."