CHD's in dogs?

Among the blogs I enjoy daily is one by a South African named Tertia. Her blog "So Close" is about her family life (with twins) after a long period of infertility. In today's post she writes about the sudden death of the family puppy. Here she reports on the autopsy findings:

A full examination is done and we have our answer. Thank goodness, thank you with all my heart, the dog didn’t suffer. She had heart failure due to a genetic disorder. She must have died instantly and peacefully. I can’t tell you how much that helps me. The thought of her suffering was killing me. She was such a sweet, loving dog.

The vet says it is fairly common. Their hearts become enlarged and simply give in. My heart feels like it has taken a severe beating this week. I’m exhausted. I feel so terribly sorry for my baby dog. I’m glad she had a good life, albeit a far too short life. And I am so glad she went peacefully.

Inherited Heart Disease
The breed's primary heart problem is Subarterial Aortic Stenosis (SAS) but goldens also face Mitral Valve Dysplasia and other valve problems.

SAS is a restriction of the aorta, usually by a ring of fibrous tissue, just after it leaves the heart. This restriction results in a distinct murmur (due to backflow and turbulence), heart enlargement, and restricted blood flow. As with CHD, affected dogs can be asymptomatic or severely crippled by this disease. SAS can also lead to sudden death, even in very young dogs. It is thought to be a genetic disease with a polygenic dominant mode of inheritance. Since many goldens have innocent (non-SAS) murmurs as puppies, breeding adults must be cleared by a board-certified veterinary cardiologist.

So, the puppy died of Wren's CHD (without treatment)! I am surprised to hear that there is even a veterinary cardiologist!