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Radioactive Iodine Service for the treatment of Hyperthyroidism in cats
Feline hyperthyroidism is a common endocrine (glandular) disorder which results is excessive release of thyroid hormone.
Clinical signs include an increased appetite, weight loss, muscle wasting, excitability, nervousness, behavioural changes, tremors, and heat intolerance. Initially a diagnosis of the condition is made with a blood test, and potentially further investigated to detect any concurrent underlying conditions such as kidney failure, high blood pressure and/or heart disease because all of these can impact on the cat’s wellbeing. Treatment for the condition can be undertaken with oral medication for the remaining life expectancy of the cat, a specialised diet, surgical intervention to remove the thyroid gland(s), or radioactive iodine therapy.
Radioactive iodine therapy can be considered the gold standard therapy with a reported success rate of 95%. It is also ideal for patients that are unsuitable for medical treatment or surgery. Most cats are no longer hyperthyroid after one treatment of radioactive iodine. The radioisotope 131I is injected subcutaneously (under the skin), after which the overacting thyroid tissue takes up most of the 131I as it prepares to make thyroid hormones. Here the 131I emits beta particles (radiation), which will destroy the abnormal thyroid tissue while sparing all other organs. The radioactivity is very local and there is no hair loss or other side effects that are associated with radiotherapy. It is well documented that 20% to 25% of hyperthyroid cats have multiple areas of hyperfunctional (over-active) thyroid tissue, which is destroyed with radioiodine treatment regardless of location. All treatment regimes for hyperthyroidism can potentially unmask renal disease; therefore, it is important to monitor this closely.
Radioactive iodine therapy is safe and effective but does require hospitalisation of the patient for 2-4 weeks. The procedure does not necessarily require a general anaesthetic or sedation. Blood samples checking biochemistry parameters, total thyroxine (TT4) concentration, and urinalysis should be carried out before any treatment is administered to check for any underlying medical conditions.
Due to the radioactive nature of the treatment strict health and safety regulations must be adhered to when nursing these patients. Cats will only be discharged once they are emitting a safe level of radiation, however strict rules as below must be adhered to for 8 days following discharge:
- Your cat must be kept cat inside for 8 days after discharge
- No children or infants in the house should have prolonged contact with your cat
- Your cat must stay out of the bedrooms (especially at night)
- You cannot hold your cat for prolonged periods of time (maximum of 10 minutes)
- You must use adhere to storing the waste produced in the litter tray if specific cat litter (World’s Best Cat Litter) is not used.
See our Hyperthyroidism Pet Health Information page for further information.
For further information on this service and the treatment of hyperthyroidism please contact us.