I*m with you Oz. A life interrupted too early is never a good thing, but I think that in many cases death is a mercy, especially when it comes to end suffering. That's an interesting difference of view between the US and Europe. I've found that in the States people tend to value life above all else, while over here it's more common to value quality of life instead. Owners of three legged dogs in the States tend to be seen as merciful, while I would see that as causing unnecessary suffering to the dog.
To me, one of the greatest acts of love toward an animal is to let it die a dignified death instead of prolonging it's life for selfish reasons. But then again, I can understand why others think differently.