Any changes in breathing should be concerning, you should keep a close eye on Lucy to see if it passes; if it seems like she is having difficulty getting enough oxygen or her gums are pale you should visit a Veterinarian immediately. Infections, laryngeal disorders, airway obstructions, tumours, poisoning, anaemia among other causes may cause respiratory difficulties. Regards Dr Callum Turner DVM
Those animals were then bred indiscriminately, and many purposely inbred for traits such as white coats, tiny size, and docile (read retarded) temperament. None of the exotic cats in wild hands can be traced back to the wild, other than local cats, cougars and bobcats, who may have been snatched from the wild in the U.S. For that reason they can never be bred for introduction back to the wild.
Big cats are very aggressive, and will sprint and chase down their prey. This can range from mobs as small as ants to as large as deer. They will also attack the player if they come within the big cat's range, or if they are provoked. If a big cat is attacked by another mob, it will fight back. Like bears, big cats will attack other mobs when hungry. Once a big cat has made a kill, it will not be aggressive until it gets hungry again. Tamed big cats won't attack each other or other mobs, unless another mob attacks it first.

Rapid breathing (tachypnea) is a respiratory disorder characterised by abnormal breathing that is rapid and shallow.  It is caused by a reduced level of oxygen, mechanical disorders (where the lungs aren’t able to expand as they should, usually due to a build-up of fluid in or around the lungs), and physiological disorders in which the cat’s respiratory centre in the brain is over stimulated.