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Radioactive Iodine Therapy for Cats with Hyperthyroidism

Feline hyperthyroidism is a commonly diagnosed hormonal disease in geriatric (over 10 years of age) cats. The disease is caused by a benign growth of cells that secrete thyroid hormones in excess of the normal levels. At The Cat Practice, our goal is to manage and hopefully reverse this disease so your cat can live a full life well into their golden years. One of the most effective ways we do this is with radioactive I-131 treatment or radioactive iodine therapy for cats.

Signs of Feline Hyperthyroidism

Signs your cat may have hyperthyroidism include:

  • Extreme weight loss in the face of a good appetite
  • Muscle weakness
  • Heart disease
  • Intolerance to stress
  • Even death, if left untreated
  • Diarrhea
  • Agitation

How Does Radioactive Iodine Therapy Work?

The thyroid gland is the only tissue in the body that concentrates iodine actively. When we administer the radioactive iodine subcutaneously (under the skin) the body readily absorbs it into the cat’s bloodstream. Once in the thyroid, it destroys the overactive portions of the thyroid gland, curing the disease in over 95% of cats (according to Ohio State University).

radioactive iodine therapy for cats

Hospitalization After Treatment

Since radiation is present in your cat’s body following the injection of radioactive iodine, your cat will need to be hospitalized until the radioactivity decreases to acceptable levels. This timeline can vary depending on your cat’s ability to excrete the iodine via the kidneys and how long the radioactive iodine is bound to the thyroid. Your cat’s level of radioactivity is measured by the Louisiana Department of Environmental Quality and they are the ones who determine when it is safe for your cat to be released. Generally, hospitalization is approximately 7-14 days.

radioactive iodine therapy for cats

Monitoring Your Cat

The Cat Practice or your referral veterinarian will schedule follow-up appointments at 1 and 3 months after treatment. We will test thyroid and kidney function. Hypothyroidism (low thyroid hormone levels) may occur at this time. If it persists, this condition may require lifelong treatment.  For those few patients who continue to have high levels of thyroid hormone 3 months after treatment, repeat treatment or other therapeutic modalities will likely be required.

Benefits of Radioactive Iodine Therapy for Cats

Other methods of treating hyperthyroidism include long-term medication which does not cure the disease but only controls it, and surgery, which could cause complications and often requires a second surgery. Dietary therapy can also manage this disease, but it consists of special food that is the only diet your cat can eat. Radioactive I-131 treatment, however, has very few side effects and is highly effective. Other benefits include:

  • No anesthesia required
  • Does not damage any other tissues or organs
  • No medication required
  • No major side effects
  • Cures the disease by returning thyroid function to normal
  • Cost-effective

Discharge Instructions

Even after your cat is released, they will still possess low levels of radiation. To prevent any spread of radiation to other family members, garbage collection personnel, or anyone else who may come into contact with your cat or their litter, you’ll need to follow certain precautions for at least 2 weeks following their release:

  • Keep your cat in a confined area and keep contact to a minimum. Casual contact is fine, but prolonged lap sitting and sleeping in your bed should be avoided.
  • If your cat does escape their confined area, clean any surfaces they touch with soap and water or a spray cleaner.
  • Pregnant women, children 10 years or younger, and all other pets should avoid all contact with the cat, their litter, food and water bowls, and toys for a full 3 weeks.
  • Wash your hands after any contact with your cat or anything the cat has come into contact with (food and water bowls, litter box, etc.).
  • Their litter will need to be collected in a separate bag from the household garbage and held for 2 weeks in a confined area (garage or another out-of-the-way part of the house). Flushable litter, however, can be flushed normally.
  • Any cat bedding will need to be washed separately from the regular laundry.
  • Use disposable plastic gloves to clean the litter box and store them with the waste.
  • If your cat needs emergency care within the first 3 weeks of coming home, be sure to inform the emergency staff that your cat received radioactive iodine therapy.
  • After 1 month, you can safely assume all normal routine activities with your cat.

If you have any questions about radioactive iodine therapy for cats, please contact us at (504) 525-6369 today!

Mr. Biggs was taken care of very well and I am so relieved to have him home again. 

- Jason H.

Absolutely love that this veterinary office is dedicated solely to the care of cats. Doctors and staff are extremely knowledgeable, friendly, compassionate regarding pets left in their care, lessening any concerns owners may have prior to visiting!

- Jasmyn S.

We love coming to the Cat Practice for vet appointments and boarding! My cat has stayed at one other boarding place and was extremely distressed when I picked him up. Every time we come here, he is happy and stress free when I pick him up! Thanks!

- Kristen T.

We have been coming since Cali was a tiny kitty and I would not go anywhere else. We are treated with kindness and friendliness and I very much enjoy going in. It has been the same kind of experience I had with my childrens' pediatric visits.

- Joyce H.

You're all absolute experts on feline health, and you give my cats the very best of care. I wouldn't take my beloved pets anywhere else.

- Laura L.

The knowledge and understanding Dr. Cousins has of felines is outstanding. Being only 1 of 80 in the nation that is specialized in feline practice makes us feel that our fur babies received the upmost care & treatement. Would highly recommend!

- Aaron B.

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