When you plan a will, you (if you're smart enough to make a will and have the advice of a lawyer) have the right to leave your money or assets as you wish. Possible heirs might not think so, though... From the Poughkeepsie Journal:
When her beloved terrier, Jasmine, died, a widow announced she would change her will and leave most of her money to the Humane Society. That's where she had obtained the dog.The woman's two adult children, upon learning of her decision, went ballistic. The children, who had seldom recently talked with their mother before this, began attacking her from all sides.
Said the woman, ''My little Jasmine gave me more joy in life than they ever have. Why shouldn't I leave my money as I please?''
My own concern is that I want to out-live any pets I have because I make a solemn promise to all of them that I will always take care of them. I don't know that if I thought my "end" was near, that I would take in a new pet.