“Case of the Month” – September 2022

Ragoth, a 4-year-old male green iguana, has always been a healthy and curious companion for owners Gene Nelson, PhD, and his wife Linda Nelson. However, late last year, they noticed tumors developing on his left shoulder. Their primary veterinarian along the Central California coast surgically removed them and diagnosed the growths as mast cell tumors (MCTs). He felt that further treatment would be necessary, as the surgical margins most likely did not capture all the MCT growth and a new MCT inside his mouth was also discovered. A referral to the exotic animal specialists at the UC Davis veterinary hospital was recommended.

At UC Davis, the 4-foot, 6-pound lizard was seen by the Companion Exotic Animal Medicine and Surgery Service, which worked with the Oncology Services to thoroughly examine Ragoth and establish a course of action. They did not find any signs of tumor spread, also known as metastasis, and recommended that Ragoth return for a CT scan to plan for radiation treatments once the oral MCT was removed by their primary veterinarian.

Dr. Nelson, a scholar with a background in radiation therapeutics in people, noted that there were only two previous published cases of MCTs in green iguanas. While the tumors are occasionally seen in iguanas, there are essentially no established protocols of care for these cases. While venturing into uncharted waters, all agreed that radiation therapy was the best choice for Ragoth, as it can be effective to clean up tumor cells left at surgical margins when additional surgery is not feasible or not ideal in other species.

Over the course of three weeks in April 2022, Ragoth received a series of 10 radiation treatments. He remained an inpatient at UC Davis during this time given the long distance he would need to travel for treatments.

Ragoth tolerated this therapy well and seemed to be on the road to recovery, but in August, many new MCTs were noted. In discussion with the oncologists, it was elected that Ragoth pursue a combination of an oral chemotherapy drug and steroid to provide palliative management of Ragoth’s new masses. As the use of the drug Palladia is a novel method of treatment in reptiles, his care team took note of results of its use in cats and dogs – the fact that 40% of them can develop signs of digestive upset such as vomiting, inappetence, or diarrhea. So, the Nelsons were instructed to monitor Ragoth’s habits at home closely (appetite and energy) to ensure he was tolerating this medication well. He was also prescribed oral omeprazole and diphenhydramine to combat the digestive side effects that the release of histamine granules from MCTs can cause.

“I thought it was excellent that the veterinarians thought through that in order to provide the best care possible for Ragoth,” said Dr. Nelson. “The set of medications has done a great job in arresting this new set of aggressive tumors. We’re now in the third week of treatment, and things look good for Ragoth. We know that we have to persist for some time, but he seems to be responding well to medications.”

The Nelsons are experienced reptile owners. Linda, a former healthcare worker and now a fine arts painter, has owned reptiles for more than four decades and introduced Dr. Nelson to the joys of owning lizards.

“When we first met, Linda said to me, very simply, love me and love my lizards,” he quipped.

Besides Ragoth, they also share their home with an alligator lizard and a bearded dragon. They emphasize that owning reptiles is not for everyone. It takes a particular dedication needed to keep reptiles as pets.

“You have to learn a lot about them,” Dr. Nelson said. “They’re cute little lizards in pet stores, but they can grow to six feet. And they can develop quite an attitude, but they can also become quite bonded to their owners.”

The Nelsons remain cautiously optimistic about Ragoth’s future.

“He’s such a nice animal,” Dr. Nelson stated. “He’s very curious and responds well to us, so we really don’t want to lose him. We recognize that this treatment may only be a lease on life for him, but we can be grateful for every day we have.”

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