Breathing fast due to stress?

Hi all.

So, my Siamese has been at my boyfriend's house since we got her about a year ago. Recently, his family hasn't had the time to take care of the many pets at his house and so I offered to take her to my house today.

It is hot here where I live and it was about a 40 minute car ride. I had the AC on the entire drive.

When we got here, she obviously wasn't happy but was very curious. I do have a resident cat and she didn't take to him very well. She's been in my room for the past 3 hours with the fan on. After I cleaned up, I came back into the room to find her tired and breathing fast. She even panted twice with her mouth open.

I put some water and food out for her, but she doesn't want to eat nor drink. It's been an hour and a half since I've noticed and she's calmed down a bit, but still is breathing faster than average. She still seems tired (but she usually is up and roaming around this time).

Any advice? Reasons why she's like this? What my next step is?

Thank you,

Absent any health issues she's either excited or scared. She is probably scared and exhausted from being that way for awhile. If she's an older cat I'd probably make an effort now to go into your room and calm her with some TLC. Younger cats can take the stress better. Either way i'd keep her away from the resident cat until she calms down. The behavior is a normal. I've got a scaredy cat just like her and it's a chore to calm them when put in situations.