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Radiotherapy for hyperthyroid cats

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Chipping Norton Veterinary Hospital has one of only 15 radioiodine units in the UK for treatment of hyperthyroid cats.

Our unit is run by vet Martin Whitehead BSc, PhD, BVSc, CertSAM, MRCVS, a Royal College of Veterinary Surgeons recognised Advanced Practitioner in small-animal medicine, who has a special interest in hyperthyroidism in cats.

Hyperthyroidism is a very common disease in older cats. It has a very gradual onset, but is eventually terminal if not treated. There is an excellent overview of hyperthyroidism in cats, including its treatment, on the International Cat Care website.

Hyperthyroidism can be treated in one of four ways. In a small proportion of affected cats a special diet can be used to manage the disease. Otherwise it can be managed with lifelong medication using tablets, drops or skin cream, or cured by either surgical removal of the thyroid gland(s) or by a single under-the-skin injection of radioactive iodine. From the veterinary viewpoint, radioiodine therapy is generally regarded as the 'gold standard' treatment, but UK environmental and human health-and-safety regulations require that the cat be housed in a dedicated unit until their radioactivity level decays sufficiently for them to be sent home.

For our unit, cats can be sent home after five to 10 days, depending primarily on the dose of radioiodine injected (this hospitalisation period is shorter than for most other units), provided the owner can meet certain restrictions for two weeks after the cat goes home. These restrictions for that two week period are described in this owner instruction leaflet.  In summary they are:

• The cat will be kept indoors and use a litter tray, and all soiled litter will be either flushed down the toilet or stored for several weeks before disposal in the regular rubbish collections.

• The cat will not sleep on anybody's bed overnight, and owners will limit the time they spend cuddling the cat.

• The cat will not be near children under 12 years old, or pregnant or breast-feeding women.

If these instructions cannot be met, either we cannot treat the cat or the cat can stay with us for another 13 days in our boarding cattery, at which time it can be sent home with no restrictions.

Some circumstances can make cats unsuitable for radioiodine therapy, the most common of which is that the cat has certain other illnesses which require essential daily medications, for example diabetes or heart failure.

If you are a vet (information for referring vets) and would like to refer a hyperthyroid cat to us for treatment, or an owner of a hyperthyroid cat interested in this treatment, please call ChippingNorton Veterinary Hospital on 01608 642547 or e-mail us at