Hi Gillian,
Paddy died from what the vet is certain was Hypertrophic Cardiomyopathy - the vet says that he has only seen a handful of cases in 25 years and has never seen a case in a kitten.
We have his brother as well as my Mum wanted two kittens - thankfully he appears to be healthy and our vet is going to keep an eye on his weight as weight loss is apparently as good an indication as any of heart probs.
I wondered if it was HCM - its just that my Sam has just been diagnosed with it (he's nearly 11) and it was only in the past few months that I'd noticed him having breathing difficulties, he'd been fine before that. The illness doesnt normally come to light until later in life, although it can take them early if they develop a clot.
His breeder (who has also become a very good friend over the years - and I've had several cats from her) was shocked and upset to hear about Sam, and sadly she's recently heard from another person who'd had a kitten from her years ago, from the same line as Sam, who has just died due to HCM, so it looks like it in Sam's case it is inherited although we can never be sure, because it can also be acquired and come out of the blue. She stopped breeding some time ago now. Sam's on medication and is fairly stable at the moment, but I know he's on borrowed time.
Its a terrible shock to lose a cat suddenly like that, I know, and as I said, perhaps Paddy's breeder is also reeling and will get in contact. Hope so anyway
I hope Paddy's brother is ok too.