Dear Most Esteemed and Knowledgeable Kitties:
I have a 17-year-old female cat named Gabby, who I’ve raised from the time she was 6-8 wks old. I believe she is suffering from hyperthyroidism — all the symptoms, weight-loss, shedding, howling/pacing, thirst, frequent urination, etc. The vet said it’s possible, but without extensive blood tests we can’t be certain. Lately her weight loss and fur shedding is worse, so I was looking online researching the disease, which is how I came across your blog and Facebook page. I was reading about the three different treatments for this disease and saw your mama’s post about whether or not to spend the money on the radioactive iodine therapy for Siouxsie. I didn’t find any follow-up articles by your mama on whether or not she went through with the radioactive iodine therapy. If she did, do you believe, looking back on it now, that it was worth it, or did it cause Siouxsie to eventually pass away? I am looking into this now, and I’m asking for your thoughts based on your experience.
Thomas: Well, Kim, Mama did choose to do radioactive iodine therapy for Siouxsie, and she says she’s glad she did it.
Bella: Radioactive iodine therapy, also known as I-131 therapy, is designed to kill overactive thyroid tissue while leaving the normal thyroid tissue alone.
Thomas: It works because the thyroid gland depends on iodine to function correctly. Because hyperactive cells take up more iodine than normal ones, the radioactive iodine kills those overactive cells but not the normal tissue.
Bella: But, back to cats, and Siouxsie in particular: the reason Mama decided to do the I-131 therapy is that it is the gold standard of treatment. Once a cat gets the therapy, she’s cured of hyperthyroidism.
Thomas: Well, in 99.99999 percent of cases, anyway. Siouxsie happened to be that one in a million cat who didn’t respond to treatment.
Bella: There are other therapies for hyperthyroidism, too: Medicine, and surgery to remove the thyroid gland.
Thomas: The medicine, called methimazole, slows the thyroid gland down and helps hyperthyroid cats gain weight and stop the behaviors associated with thyroid disease. Medical treatment seems less expensive at the outset because methimazole is not a very expensive drug — especially at the doses used on cats — but if you have a relatively young cat, the cost of medical treatment, between the pills and the frequent blood tests needed to monitor thyroid function, will actually exceed the cost of I-131 therapy in the long run.
Bella: The other treatment, surgery to remove the thyroid glands, leaves the cat hypothyroid: he doesn’t have enough thyroid hormones and gets sick because of that! Hypothyroid cats are on medication for the rest of their lives, too.
Thomas: And surgery may not be a cure because kitties with hyperthyroidism can have thyroid tissue growing in other parts of the body. That happens if the hyperthyroidism is caused by cancerous cells that spread beyond the thyroid glands.
Bella: Would Mama do I-131 treatment again if one of us became hyperthyroid? You bet she would! It’s the gold standard of treatment, and then she wouldn’t have to give us pills every day.
Thomas: Kim, you talked about extensive testing to determine whether Gabby is hyperthyroid. We don’t necessarily think it’s that extensive. Basically, it’s a standard senior blood panel, which will reveal the level of thyroid function along with kidney and liver function and a whole lot of other things. If Gabby’s senior blood panel reveals hyperthyroidism, your vet may recommend another blood test, the free T4 (FT4) test, which is a more sensitive test to determine how much thyroid hormone is in your kitty’s blood.
Bella: One thing you should know is that treating hyperthyroidism can unmask kidney disease.
Thomas: A hyperthyroid cat is peeing a lot more, so there’s a lot more fluid going through the kidneys and filtering out toxins. That can make it seem like Gabby’s kidneys are working better than they are, because of the lack of toxin buildup in the blood.
Bella: In Siouxsie’s case, her treatment did unmask mild kidney disease (Stage 2), but she never needed to get fluids or medical treatment for her kidney issues.
Thomas: But depending on your cat’s degree of hyperthyroidism, you may find there is more severe kidney disease present.
Bella: The most important thing to focus on here is not the fear of kidney disease, but your kitty’s quality of life. Cats with untreated hyperthyroidism aren’t enjoying as good a life as they could.
Thomas: We don’t know if it hurts to have hyperthyroidism, but we imagine it can’t be fun to be hungry and thirsty all the time, and that agitated or anxious feeling isn’t great, either.
Bella: If nothing else, we strongly recommend that you go to your vet, have a new blood panel done, and see where Gabby is at in terms of thyroid and kidney function.
Thomas: If she is hyperthyroid, you may want to try treating Gabby with medicine first. Your vet will probably want to do another blood test a month or so into treatment to see if she’s getting enough medicine to effectively treat the thyroid disease and to see how her kidneys are doing.
Bella: This could also give you some time to get some funds together to do the I-131 treatment if you decide to go that route.
Thomas: We’d recommend having a serious talk with your vet about the benefits and risks of I-131 therapy in terms of Gabby’s age and her overall health.
Bella: Whatever treatment you choose, you’ll find that you’ve got a whole new cat once her hyperthyroidism is under control.
Thomas: What about you other readers? Have you had a hyperthyroid cat? What treatment did you choose? How do you feel about your choice? Please share your thoughts in the comments.
Thanks for sharing this article as well as the original posting about Siouxie’s radioactive iodine treatment.
We also have a cat that was non-responsive to the I-131 treatment. What treatment option did you guys take after Siouxie’s I-131 treatment was ineffective?
Three months ago, we bit the bullet and spent $1800 on I-131 for our 14 year old baby as her methimazole pills were becoming less effective over the last year or so. It was a huge stretch to spend that kind of money, but we were determined to do our best for her health and quality of life. At the 1 month and now 2 month marks, her T4 levels are lower than they were but still absurdly high (14.6 then 20.4). We are at a bit of a loss for what to do at this point.
To anyone reading up on I-131, I would like to emphasize that our case of non-responsive to treatment is very rare (some vet’s post 1%, others <5%). In retrospect, I really wish we would have been able to afford this therapy very early in her diagnosis. I believe it would have been much more effective since her starting levels of T4 were 11 (instead of 41 at this stage). So for newly diagnosed cat's moms and dads doing their research, I absolutely endorse this as the best treatment option if within budget and if the cat is a good candidate.
My daughter had a cat named Cookie, who, at fourteen years of age, began to lose weight, have a rapid heart beat and eat constantly. My daughter lives across the street from me and Cookie was a real homey cat, never crossing the road to visit me until that last year. She would cry at my door even after she was fed by my daughter. I thought it was thyroid disease but my daughter, who was on a limited income, did not take her to a vet since she seemed normal in every other way. If I had not 5 cats of my own (two from a colony that had health issues) I would have taken her but being as she lived almost fourteen years without ever being sick and only receiving rabies shots we thought she was doing pretty good. One day she disappeared and we found her under the house having passed away. To treat or not to treat an elderly cat is the question. Some people may pay thousands of dollars to prolong (especially an elderly cat’s) life, others may not be able to afford this and allow their pets to pass on. Personally, if Cookie had been my cat, I would have sought treatment. We cannot always answer for our children but I do know that Cookie had a wonderful life for many years and her memorial cross sits in the yard always draped with a little flower.
I was grateful to read this about thyroid treatment in cats. Having been adopting out cats and having cats ouf my own for over some 20 years thankfully it is not something I have come accross. It sounds really tricky in the choice you make. Especially if you are trying to decide for a dearly loved one that happens to be very elderly.
I have been put in that situation. I have been taught many lessons by my loved ones over the years and one is when to let go as well as when to just treat and keep comfrotable.
We as humans, myself included would keep them here forever, however just speaking from my perspective I have finally learned to look deep and ask , what is best for my friend. And I just buying them uncomfortable time or will this heal my friend. Its so hard sometimes.
Very grateful to read about thyroid disease in cats. Now I want to research it myself.
Thanks for posting the information to get me started.
I had the therapy done for my 13 yr old female cat, Patches back in spring of 2012. She lived until 2019 almost exactly 7 more years!