Paws and Effect

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.

~ Kim

A black cat rests in a heated leopard-print bed

Siouxsie had I-131 therapy. Photo CC-BY-SA JaneA Kelley

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.

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