Radioiodine therapy

What is hyperthyroidism?

The thyroid gland is a small organ in the neck that produces hormones that regulate the metabolism. If the thyroid gland releases too many hormones, this is known as hyperthyroidism. This can have various causes, such as a benign tumor or an autoimmune disease. The symptoms of hyperthyroidism include

• Weight loss despite an increased appetite
• Restlessness, nervousness, aggressiveness
• Palpitations, high blood pressure
• Increased body temperature, increased panting
• Hair loss, poor coat quality
• Vomiting, diarrhea

An untreated hyperthyroidism can lead to serious secondary diseases such as heart failure or kidney failure. It is therefore important to make the diagnosis early and start suitable treatment.

How does radioiodine therapy work?

Radioiodine therapy is based on the principle that the thyroid gland needs iodine to produce hormones. The radioactive iodine isotope iodine-131 is administered to the dog either as an injection or as a capsule. The iodine-131 enters the thyroid gland via the bloodstream and accumulates in the overactive cells. The radioactive radiation kills these cells without damaging the surrounding tissue. The remaining iodine-131 is excreted in the urine.

Radioiodine therapy has several advantages over other therapies:

• It is very effective and in most cases leads to a permanent cure.
• It is very gentle and avoids the risks of surgery or the side effects of medication.
• It is very simple and only requires a single administration of iodine-131.
• It is relatively inexpensive and saves the dog long-term treatment costs.

What needs to be considered with radioiodine therapy?

Radioiodine therapy is a safe and effective treatment for dogs with hyperthyroidism. However, there are a few points to bear in mind before and after the therapy:

• Before therapy, the dog must be thoroughly examined to determine the exact cause and severity of the hyperthyroidism. This includes blood tests, ultrasound examinations and possibly a scintigraphy (imaging with radioactive substances).
• Before therapy, the dog must be fed a low-iodine diet for a few weeks to increase the uptake of iodine-131 into the thyroid gland.
• After therapy, the dog must be isolated in a special veterinary clinic for several days to weeks to protect other animals and people from the radiation. The duration of isolation depends on the dose of iodine-131 administered.
• After therapy, the dog must be monitored regularly to check the success of the therapy and to detect possible complications. This includes blood tests, ultrasound examinations and possibly a repeat scintigraphy.
• After the therapy, a temporary or permanent hypothyroidism may occur, which must be compensated for with medication. However, this is rare and usually easy to treat.