Lately when Roxy sees another cat he does this thing where he forces air out of his nose VERY loudly (well very loudly for a cat). Once in a while he does it when another cat is not around, but he'll stand there and look around very alertly and blow out a heavy breath in each direction he looks. Otherwise he acts like nothing is wrong, when he's in the house he's normal and other times when he's outside he's normal also. It could be coincidental that he does this when he sees other cats so I'm just wondering is this some sign of a health problem? He's also gotten in at least one or two cat fights lately, but with the cat he always hangs out with and neither of them did any damage, but I can't understand why suddenly they have all this aggression toward each other. The heavy breathing occurs when this particular cat is around but today when I went to let him in the house from the garage he started doing it when I picked him up, but when we got in the house it was fine. Any thoughts? He's definitely not struggling to breath or anything, it seems like he does it on purpose and only when he breaths out. Its freaking me out a little lol.