I had a female die two years ago of HCM and microcardia, as confirmed by medical necropsy. I had zero warnings. She was active, healthy, happy, and only five years old. She had one litter of seven kittens, three years prior to her untimely demise. She was not in-bred and was an exceptional F4 silver female out of a Egyptian Mau line. Unusually loving one spring morning and lying dead on the floor of my bedroom that evening. She was a breeder I got as an adult, I also had her son as a kitten. I am so happy I did not breed her myself. I hope her son does not have HCM. I am going to have him scanned very soon.
I urge all breeders to scan for HCM. That is the only way to reduce the occurrence in the breed, if it is indeed genetic. The fact that it is more prevalent in purebreds than mixed breeds strongly suggests it is genetic. Finding her in my bedroom was one of the most traumatic experiences of my life, second only to seeing my grandmother die of leukemia.
I think the data is too new to see if the Savannahs have a distinctive predisposition to HCM, but I expect to see that connection made in the next few years and the next several generations of Savannahs. The Bengal breed has been linked to HCM. Savannahs are a little newer than the Bengals and a little less main-stream. To me, I believe that there are less generations of Savannahs, so there has been less mixing of the same isolated gene pool of the available breeders. As the gene pool continues to mix, I believe we will see a higher occurrence of HCM and other cardiac illnesses. I also acknowledge the role microcardia had in her death. She had little hope with the compounded problems, even if there would have been a sign to bring her to the vet before it happened.
Do not discount the number of deaths that go undiagnosed. The average pet owner is not going to spend the $120.00 to have a necropsy done. I'm need even sure if the average vet will offer to do one. I told my vet that I need to know what happened. If it was a poison, I need to know. I have 6 other animals in my house. I just needed to know what happened. It was the best $120.00 I could have spent though. I received so much closure knowing that there was little I could have done.