Jessi went up the stairs and paused to stroke the purring cat.
Kittens can be heard purring as early as one week old.
Sunny perched on his thigh, purring as he patted her.
His breathing and purring, when relaxed, are sometimes a little congested/labored sounding, though he doesn't appear in any discomfort.
There has been an ongoing debate about the reason for cat purring sounds.