I'd like to share my experience with feline panting.

My Chazmayne kitten (about 6 months old) panted when he played. He loved leaping and doing aerial acrobatics when enticed with a teaser wand toy. I never had a cat that panted, and upon investigating this symptom on the internet I was very scared at his possible diagnosis . . . cardiomyopathy. When I had taken him to vet for his initial exam she detected a murmur only upon compression of the heart. She was not concerned and went ahead with his neutering, which he came through like a champ.

AFTER that was when I noticed the panting, and insisted upon a referral to a cardiologist. He did an ultrasound to the tune of $500.00 and determined that there were no cardiac defects and stated that "sometime kittens pant when excited and playing". I no longer am concerned and his panting has diminished, although it could be due to the fact that I don't play too long or hard with him anymore, as he is nearing his first birthday and so not QUITE as rambuctious as he was when younger, but he is still a pistol . . . to his benefit he is also a looker and someone inquired if I would be willing to part with him and I said sure if you want to reimburse me the $500.00! Lol . . . just kidding as I am way too attached to him . . . yeah, by my purse strings! Again, I'm just joking as I regard my cats (all 8 . . . gosh, I need to update my Avatar) as my children and could NEVER relinquish any of them.

Well, I hope your kitty has a positive prognosis like Chazmayne, and the panting is nothing serious.