Kenjis kittens should all have left us in December, but a week or two before they had their 2nd vaccinations I noticed that Microwave (my daughter chooses kitten names!) was breathing faster than he should be. At the time of vaccination I mentioned this to the vet along with the possibility of him having funnel chest (https://www.petmd.com/cat/conditions/musculoskeletal/pectus-excavatum-cats) who agreed that his respiratory rate was fast, but as he appeared to be in excellent health, heart sounded good, exercise tolerance was fine, no coughing and he has an extremely good appetite so we decided to just monitor him initially. A week or so later I was still concerned so we took some xrays. My own vets couldn't see anything obvious so they sent them to a specialist. The specialist initially said all looked normal and recommended we do an ultrasound of his diaphragm, but later phoned back to say on closer inspection they felt he had a very mild case of funnel chest which he would hopefully mature out of. Despite this I felt I wanted further confirmation that there was nothing else going on so I had the ultrasound done. This was inconclusive as the liver was obscuring some of the detail so it is still possible the diaphragm was torn and that the liver was blocking the tear. Based on this the decision was made to keep him with us, at least until he is neutered next month when he will be xrayed and ultrasound examined again.
He is one of the best kittens I have bred with regard to personality, he's bright as a button and adores human company. He has taught himself to play fetch which he will do for long periods of time :) He will also launch himself at you if you stand near him in order that he can hitch a ride on your shoulders.