Kitty panting

Last night, I was playing with our two cats for about 30 minutes using a toy mouse tied to a plastic stick (they LOVE that toy). They were playing pretty hard, and after about 30 minutes, one of them was panting very hard with her mouth open and tongue hanging out. She looked like a dog! It freaked out the other cat. I've never seen a cat breathe that hard before. When that started, I put the toy away and let them calm down. Is that normal?

It's normal if they get really worked up, stressed, or hot. Just like dogs.
The cat that did this isn't over weight is he/she? And your home is well ventilated an cool even during summer? Does he have any breathing problems through his nose ever?

Actually, she is NOT overweight but does seem to breathe loudly sometimes. She snores, too. We may take her to get looked at. The other cat never makes a peep when she breathes.

We usually keep our house cool.

I have seen cats pant when they exercise to an extreme. Actually, I have three and mine never pant, even when they run around like crazy. (but I've seen friends cats do this) I have read that cats with louder(or faster) breathing can have feline asthma so it probably is good to get it checked out. Probably nothing for you to worry about though.

What breed is this cat by the way? Some breeds can just naturally have a harder time breathing through their nose because of the way they were bred.

I've never seen a cat do it during play, least not a healthy one. But I have seen them do it under extreme heat or stress.

Wouldn't hurt to get it checked out at any rate.

Hi
Both of my older cats have panted also, just like yours and they are not overweight. My torbie girl pants when I play hard with her, making her run back and forth on my bed trying to get the "stick end", and my male Siamese will pant when he walks around outside for a while.When I first saw them pant, I laughed because I thought it looked so funny to see a cat pant and not a dog.
~Anne