panting like a dog????

I have a quick question. I have a 14 month old female cat and she is on the heavy side. she eats everythign in sight except her own food. we've had to mix both our cats food together jsut so she'll at least get some weight management food in her. today she got out and when i brought her back inside she laid down on the floor and started panting like a dog, mouth open adn everything, the thing is she wasn't running around or anything outside jsut laying in our neighbor's driveway. got any ideas on why she may be doing this?

Cats pant when they are stressed out. I would let her sit in a quiet room for a while. I would also up her play time or add a few extra sessions to boost her metabolism!

When I brought Amber to the vet a few weeks ago I had the windows downs, not quite thinking. And she started to pant. I already knew she was scared from the ride so I put the air on and the windows up!

Stress is bad!

Panting can be caused by stress, asthma, heart disease, I would take her in to be checked if it were me. Run her blood levels and see if she is okay.

thanks for the replys. i was thinkgin of bringing her in because the only thing i'm really worried about is her being overweight. i had a cat that got diabetes at a pretty young age mostly because he was overweight. i'm pretty sure she's not stressed or anything because she loves to go outside and does every chance she gets. lol. she's about due for a full blood check anyway. thanks again!