Hyperthyroid Cats

Hyperthyroidism is a very common disease in older cats

Radioiodine therapy for hyperthyroid cats

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 low-iodine diet can be used to manage the disease. Otherwise it can be managed with lifelong medication using tablets, oral 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.

We sometimes require some tests be done prior to radioiodine treatment, to check that your cat has no health problems that could cause a problem during the treatment period.  Almost all such tests can be done by your usual vet – often they have already been done in the process of diagnosing the hyperthyroidism.  Otherwise, no preparation is required for radioiodine therapy other than, if your cat is on a thyroid medication, that must be stopped a week before coming to us (if your cat is on the special low-iodine diet, that must be stopped two weeks before coming to us).

Cats can be sent home after three to 10 days (a shorter period than for most other radioiodine units), depending on the dose of radioiodine injected and how quickly the individual cat excretes radiation, provided the owner can meet certain restrictions for two weeks after the cat goes home. The restrictions for that two-week period are described in this owner instruction leaflet. 

In summary they are:

For 1 week

 For one week, the cat will be kept indoors and use a litter tray.

  • During this one-week period, the cat will not sleep next to anybody on their bed overnight, and owners will limit the time they spend cuddling the cat.
  • During this one-week period, the cat will have no direct contact with children under 12 years old, or pregnant or breast-feeding women.

For 2 weeks

For two weeks, all soiled litter will be either flushed down the toilet or else stored for several weeks before disposal in the regular rubbish collections.

If these instructions cannot be met, either we cannot treat the cat or the cat can stay with us for that one-week period (two weeks if the owners are unable to flush or store the used cat litter) in our boarding cattery, at which time it can be sent home with no further 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 you are an owner of a hyperthyroid cat interested in this treatment, please call Chipping Norton Veterinary Hospital on 01608 642547 or e-mail us at riu@chippingnortonvets.co.uk.