Treating Dogs' Thyroid Cancer With Radioiodine

In dogs thyroid cancer is not very common. However, there are very few symptoms so if your dog does develop this kind of cancer then it could be hard to spot. As with any cancer, catching the disease early will make it easier to treat.

Symptoms of Thyroid Cancer

The thyroid regulates your dog's metabolic rate. A growth on this gland can affect your dog in a number of ways and cause hyperthyroidism. Often symptoms are hard to recognize but they might include:

  • Excessive urination
  • Increase in appetite
  • Weight loss
  • Nervousness or jumpy behaviour

Certain breeds of dog are more likely to develop thyroid tumors than others, including beagles, golden retrievers and boxers.

Treating Thyroid Cancer with Radioiodine

Radioiodine therapy is an effective way of treating canine thyroid tumors. Radiation therapy is used when surgically removing the tumor would be too risky, or if the vet wants to make sure that all of the cancer is destroyed.

Radioiodine is a radioactive form of iodine. Iodine is a chemical which is only naturally absorbed by the thyroid gland so only a small amount of radioactivity is required when this treatment is being administered.

The procedure usually begins with a technetium scan. This is a radioisotope which is absorbed by the thyroid. When a gamma camera is used to scan your dog, the thyroid tumor will show up. This allows the vet to measure the correct dosage of radioiodine for the size of the tumor. The iodine is administered via a subcutaneous injection, similar to the way your dog would receive a vaccination.

The radioiodine will destroy the thyroid tumor and any affected thyroid tissue will regenerate itself so the thyroid can function as normal again. Normally, this happens within a couple of months of the treatment.

Side Effects of Radioiodine

As radioiodine is radioactive, it poses a risk to those around the dog. Normally, the dog will be hospitalized for a period of time afterwards to allow the radioactivity to leave his system. The radioactivity will be present in the saliva, urine and faeces of your dog and touching your dog's waste or coat could result in contamination.

After a few days, however, enough radiation will have passed through your dog for it to be safe for him to come home. Your vet will give you specific guidelines about how to deal with your pet's faeces while there is still a risk of radioactivity and may also suggest a limit on how long you can spend with him each day.

For the majority of dogs who need radioiodine treatment for thyroid tumors, the procedure only needs to happen once for your pet to be cured. Side effects can occur with radioiodine but only with larger, repeated doses. Therefore, your dog shouldn't suffer any side effects with only one dose for a thyroid tumor.

After the treatment, your dog will need to see the vet every month or so for certain tests and a physical examination. Radioiodine is an advanced procedure but is highly effective and, after only one treatment, could cure your dog of any thyroid tumors and allow him to lead a normal life again.