In scintigraphy, or nuclear diagnostics, radioactive material is administered to the patient. A scanner is then used to detect areas where this material accumulates excessively, which often indicates sites of inflammation or tissue damage. Scintigraphy is particularly useful for areas where taking X-rays or performing ultrasounds is challenging, or when pinpointing the source of pain is difficult.

This technique offers numerous possibilities and advantages, particularly for diagnosing orthopedic conditions or thyroid problems in animals. 

Treatment
For cats with hyperthyroidism, four treatment options are available: thyroid medication (oral or topical), surgical removal of the thyroid gland, a special diet, or treatment with radioactive iodine (I-131). Medication is the most affordable option in the short term but must be administered for life. Surgery involves a one-time cost but carries significant risks and potential complications. Treatment with radioactive iodine is globally recognized as the most effective therapy for hyperthyroidism in cats. Lingehoeve Diergeneeskunde is the only veterinary clinic in the Netherlands that has been treating cats with thyroid problems using radioactive iodine for many years.

Radioactive iodine therapy

Felimazole challenge test

For years a Felimazole challenge test was performed before starting treatment with radioactive iodine. Nowadays, this test is only used when there are insecurities about kidney function. For cats with creatinine levels below 50% of the normal cut-off it’s not necessary to perform this test.

Thyroid scan (scintigraphy)
First, a thyroid scan (scintigraphy) is performed to confirm the diagnosis of hyperthyroidism and to identify the overactive thyroid tissue. For this purpose, technetium (Tc-99) is administered to the cat. A thyroid scan allows us to determine whether the thyroid enlargement is unilateral or bilateral. Additionally, it can also help locate ectopic thyroid tissu. After scintigraphy, radioactive iodine is administered.

Treatment
For the treatment with radioactive iodine, a single injection is administered. As I-131 decays, radiation is released. This radiation specifically targets the thyroid tumor, affecting only the overactive thyroid cells. Afterward, the remaining thyroid cells can restore normal thyroid function, and the cat is no longer affected by hyperthyroidism.

Bloodwork and Blood Pressure
After the thyroid scan and the administration of the I-131 injection, additional diagnostics are carried out. Blood tests are performed to measure thyroid hormone levels (T4), kidney values (urea, creatinine, SDMA) and electrolytes. Additionally, the cat's blood pressure is measured. 

Veterinarian
The information above is meant for veterinarians who want to refer a patient for treatment with radioactive iodine. Are you the owner of a cat with thyroid problems? If so, please refer to the information below for guidance on treatment options using radioactive iodine. For more details, click here

Costs
The complete treatment for a hyperthyroid cat with radioactive iodine includes the following:

• Performing and interpreting a thyroid scan
• Hospitalization of the cat in the quarantine area
• Injection with radioactive iodine (I-131)
• Post-treatment blood pressure measurement
• Blood tests for T4 and kidney values (urea, creatinine, SDMA)

The total cost for the treatment is €1.825 (effective from 01-01-2025). We also offer the option of performing only a thyroid scan. The cost for the thyroid scan alone is €402,58.

Referral for radioactive iodine treatment
Would you like to refer a patient to our clinic for possible treatment with radioactive iodine or a scintigraphy scan?

You can contact us by phone at +31 488 482900 or by email at schildklierkat@delingehoeve.nl.

Please ask for the thyroid cat team, as they are the primary point of contact for nuclear medicine in companion animals.