Q:I have an 18-year-old female who was diagnosed CKD in 2012. I have maintained her with increased water in her food, and it's only recently that she started requiring subQ fluids (according to my vet). However, she was diagnosed hyperthyroid a year ago. She takes 2.5mg/day of methimazole and the hyperT is well controlled on it. Her last T4 was 1.9 and her Free T4 was 37.3. However, as I know hyperT only gets worse over time, I wanted to pursue radioactive iodine treatment (I-131) to "cure" it. (I'm aware of the chance of hypothyroidism after the treatment.) My vet is totally against it because of my cat's age and CKD, but a local vet hospital is very experienced in giving I-131 to kidney-kitties. Is I-131 something I can consider, or should I put it out of my mind because of my cat's age and health? As a reference, her last BUN reading was 77 and her creatinine was 4.9 mg/dl (up from 64 BUN and 3.9 mg/dl creatinine in June) She is otherwise amazingly healthy, happy, and active, with a great appetite. No vomiting or diarrhea. She even still has all her teeth, something that amazed my vet!

If us vets could form a band, it would be a 70’s soul group, and we would groove like this:

So I'd like to know where, you got the notion
Said I'd like to know where, you got the notion
(To rock the boat), don't rock the boat baby
don't tip the boat over
(Rock the boat), don't rock the boat baby
(Rock the boat)


I’d be the guy wiggling on stage right.

Sometimes if a cat is just like you say - amazingly healthy, happy, and active, with a great appetite, but something in their treatment plan can be made theoretically better, we still recommend not to rock the boat. Because theoretically better doesn't always mean the cat will get the benefit.

Now for your kitty, I don’t worry about age when considering most kinds of therapy. And once they show stability on a trial of medication for hyper t4, I'm not worried about worsening CKD as an absolute reason not to do it. So I have had 17 and 18 year old's go through radioiodine therapy with no problems. FYI for those not in the know - it’s an injection you give to a cat to resolve their thyroid issues. The procedure is not painful. They have to stay in the hospital for 3 to 7 days, depending where you go. People worry about CKD getting worse after you treat a cat for thyroid issues but the fact is, uncontrolled thyroid is a bigger menace to the body (and possibly the kidneys too).

But sometimes you don’t want to rock the boat. Sometimes preventative medicine keeps the water calm. Either is OK, at the end of the day you trust your gut on this to make the judgment call.

Dr. Kris