Dot is a lovely senior cat who first came to us for a check-up at 15 years of age. Her behaviour had been changing at home in the months prior. She had been starting to call out to her owner more and her vision and hearing seemed to be deteriorating. Dot had also developed diarrhoea.
On examination, our vets felt that Dot was slightly underweight, had a scruffy rough coat and seemed to have a larger-than-normal thyroid gland. She also had evidence of bacterial gastroenteritis.
As part of the check-up for a senior cat, we run regular comprehensive blood and urine screens to assess the function of all the internal organs. The blood tests help us identify disease developing or in the early stages so that we can start treatment earlier and get a much better result in the long term. A blood sample was collected from Dot and submitted to the laboratory for analysis. Meanwhile, Dot was started on some antibiotics for her gastroenteritis.
Dot’s blood test results were strongly suggestive of hyperthyroidism. Her thyroid hormone count was 166 which was nearly four times the upper limit of normal. We were also able to determine from the blood tests that all of her other internal organs were functioning appropriately.
Hyperthyroidism is a very well-recognised disease in older cats. The disease is primarily caused by overactive cells in the thyroid gland that release excessive amounts of thyroid hormone. An excess of thyroid hormone has effects all over the body and leads to a drastic increase in appetite but weight loss at the same time, loss of fur condition, behaviour changes and is directly linked to hypertension or high blood pressure, as well.
Treatment for hyperthyroidism comes in three forms: medical management, surgical intervention and radioactive iodine therapy. Each case must be approached separately to determine the most appropriate treatment option. After discussion with Dot’s owner, we decided to proceed to radioactive iodine therapy as it is non-invasive and often provides a curative result after a single treatment. This meant that Dot could avoid having surgery and Dot’s owner could avoid having to give her medications twice a day for the rest of Dot’s life.
The effects of radioactive iodine treatment are permanent. The treatment involves an injection of radioactive iodine which is selectively absorbed by the thyroid gland, allowing the radiation to kill off the abnormal overactive thyroid cells. Before progressing with the treatment, we needed to know how well Dot would respond to treatment and also if treating the hyperthyroidism would ‘unmask’ underlying kidney disease. The two diseases are extremely common in older cats and can be directly related.
We started Dot on methimazole gel, applied to the inside of Dot’s ears every morning and night for one month. A second blood screen after that month revealed an excellent result: Dot’s thyroid hormone count was now 11.4, well within the normal range and not too low either. At the same time, Dot’s kidneys appeared to be concentrating her urine well even after treatment for hyperthyroidism. Not bad for an older girl! Dot was an excellent candidate for radioactive iodine therapy.
Dot was referred to the University of Melbourne Veterinary Hospital in Werribee for her radioactive iodine treatment. The treatment went extremely well and Dot was allowed to go home after a period of quarantine at the hospital to allow the radioactive substances to exit her body.
A follow-up blood screen was performed after 1 month to assess the effectiveness of the radioactive iodine and recheck Dot’s kidneys. Our Vets were very happy with the results as they showed that Dot’s thyroid levels were again within the normal range and her kidneys were still doing very well. Dot has responded well to the radioactive iodine treatment and is able to go about her day without needing to be medicated morning and night, every day. We will continue to monitor her thyroid levels to ensure that we continue to have her at her best.
Dot is an excellent example of a senior patient coping with disease that was diagnosed based on the results of a senior blood screen. She has been a great patient and we are happy we were able to get a great result efficiently with the radioactive iodine treatment. She is now starting to gain the weight that she had lost, just in time to welcome to her home a new kitten who was adopted through our adoption kitten program. We wish Dot and family all the best in 2015 and look forward to seeing her again soon.