Why does my cat breath with her mouth open?

I have a cat, her name is Missy and she's 7 months old. When she gets very excited, after running, she breaths with her mouth open and sticks out her tongue for a few seconds(exactly like dogs). She's done that since I got her, she was 2 months old. I brought her to the vet, did a blood check and she was completely fine. He listened to her heart and lungs and he said she was perfectly fine. We also did an x-ray but again everything turned out to be normal...(heart and lungs) I want to spay her soon but I don't wanna make a mistake... Maybe that's just her way of showing her excitement, kinda like dogs. She starts doing that after 1 minute of play, so she gets tired very fast... She also hates warm places...likes going in the fridge...staying next to the window when outside is freezing cold. I 've had a cat before but she's never done this. What would you suggest?

Here's a video with her while breathing like that:

Thank you,


Marie

Smudge did that many times after running around. I was worried it was a heart problem or something, but he checked out fine and it stopped after he was 9 - 12 months old.

Mine all pant when racing around, especially with the very hot weather we are having here.

My almost 2 yr. old Go used to pant like Missy before he turned 1. He was a very active kitten. Go does not do it anymore.

Missy is so cute! I love how she pants like a dog I'm not sure what's up with that. Holly Golightly's mouth hangs open when she gets excited or startled but she closes her mouth shortly after. Holly also pants like a dog when she's nervous in the carrier en route to the vet. I thought she was having a heart attack (my roommate's cat panted before she suffered a cardiac arrest) but the vet said panting could be an anxiety symptom.