Safety for pet cats after Radioactive Iodine

I don't believe it's necessarily that pets have a higher tolerance.

Instead, it may be that because thyroid cancers are mostly very slow-growing, the impact of the damage we might cause to our pets may take longer than their typical lifespan.

That said, cats can have faulty thyroids - I have known several people whose cats have had to be medicated although I believe overactivity is more common than under. .

Your cat can't consent to spend time with you whilst you are glowing. They can't understand to stay 1m away when they want to sit on you all the time. 

I was very careful with my three cats after RAI. It was hard, but I needed to protect them. The youngest at that time was just 2 years old. He's now 15 and I'm so glad I upset him for a couple of weeks in order to not spend that last 13 years worrying that I might have harmed him.