“Right now we’re very happy,” said Silvie Tucker of her guinea pig, Lucy. “She’s definitely gaining weight and she’s looking good.”
Radioactive iodine is a sophisticated tumor-killing treatment which is well-established for use in cats and even humans.
But the case of Lucy the 4-year-old guinea pig was a new challenge even to two highly experienced BluePearl veterinarians, who had never before been asked to treat a guinea pig for an overactive thyroid gland.
Tucker was glad to hear there might be an answer to her guinea pig’s condition. Lucy had been losing weight, even though she seemed to be eating normally. Her primary care veterinarian gave Lucy medicine for hyperthyroidism, but Lucy’s weight would still sometimes drop sharply.
Lucy’s health is very important to Tucker, who loves animals but is allergic to dogs and cats. All four members of the Tucker family enjoy Lucy’s outgoing personality. “She’s very inquisitive and adventurous – she has none of the shyness and fearfulness of a typical guinea pig,” Tucker said. “She is truly special to us and we love her so much.”
As Lucy’s condition persisted, a primary care veterinarian recommended a visit to Dr. Peter Helmer, who heads BluePearl’s exotic animal medicine service in Florida.
Helmer considered multiple treatment options for Lucy, including surgically removing a tumor in Lucy’s throat that was probably causing her condition. But surgery is invasive, and may not eliminate all of the tumor.
Helmer thought there might be a simpler and safer treatment for Lucy. To find out, he began reading the scientific literature and found what he was looking for: A single journal article that described the use of radioactive iodine, also called I-131, in a guinea pig.
I-131 has a unique way of fighting an overactive thyroid gland. Normally, the thyroid gland absorbs iodine and uses it to make thyroid hormone, which helps regulate several processes in the body. But in hyperthyroidism, a tumor sucks up the iodine at an excessively fast rate. The thyroid gland responds by producing too much hormone, which speeds up the body’s metabolism and causes dangerous weight loss.
Helmer proposed injecting Lucy with I-131, which is a radioactive isotope of the element iodine. If all went well, the tumor would suck up the radioactive iodine, which would kill or cripple the tumor. But the radioactivity level is so low that it would not harm the rest of Lucy’s body.
Tucker decided to go forward. Fortunately, the use of I-131 is among the medically advanced procedures available at BluePearl’s Tampa hospital. BluePearl employs many veterinary specialists who have received advanced training to become experts in their field, and who use advanced diagnostic equipment such as CT scanners, ultrasound and others.
Dr. Erick Mears, a BluePearl veterinarian who is board-certified in internal medicine, performed the procedure, injecting Lucy with the radioactive iodine.
At that time, on June 8, Lucy’s weight was 540 grams – about 1.2 pounds. About two months after the treatment, on Aug. 18, Lucy’s weight shot up to 711 grams, more than a pound and a half. Her body weight had increased by nearly one-third.
Lucy’s thyroid hormone level had previously climbed to 10, far above the normal levels of 2 to 4. But after the treatment, her thyroid level dropped to 4.2, just a hair above normal levels.
“It’s very satisfying to see that Lucy is doing so much better,” said Mears, who is medical director of BluePearl’s Florida hospitals.
“I’m glad we were able to find this nice solution for Lucy,” said Dr. Helmer. “This risks of this procedure were low and the rewards for her are very high.”