I want to learn more about animals, and I can't figure this out!

It is basically because of their heart rate which is 60 - 160 beats a minute, and cats are 150 - 260 a minute, where we are 50 - 100 beats a minute. Other issues that pertain too a certain breeds. The oldest dog was 29 and the oldest cat was 31!!!!!

Certain breeds - especially when they come from "CLOSE" Lines can die very young. Certain Great Danes are considered old at 7!!!! Mongrels and REALLY PUREbreds - with no inter heritage - can live till 14/15. I had a PURE Irish Setter and she was almost 15 when she passed away.

Certain breeds are more prone too cancer as well, so when you have one of these "Designer" breeds, I believe, you can be asking for a LOT of heartbreak. If you think that tiny dogs are more prone too seizures, and larger dogs are more prone too hip dysplasia and heart problems. When you start mixing them it is inevitable that there will be problems.

I cannot get over these new designer dogs, not too long ago they were called MUTS!!!!!!! And you paid $50 for one, now they ask $1,200 it's CRAZY!!!

Wow I didn't know this is because of the hart rate. And what bread dog was this that has lived to age of 29?
How many dogs live to die form normal death and not from a seizure or hart problems?
And is there something that one can do to prevent these kind of things?