Why can't we have normal cats?

Why? I just want to know what's so difficult about getting a normal cat without some kind of issues. First, it was Katie and her digestive issues that had us at the vet at least once a month before I figured out how to make her own food. She's now quite healthy and playful, but just as I feel confident about her, Denali is on the fritz. Not that he was ever normal to begin with, he does occassionally have seizures. The thing is, he's developing sores on his back. We aren't sure if it's attack of the Butterball or if it's some other kind of disease. He seems to be losing weight too. Now, of course, my first thoughts are a dread fear of losing him. I honestly don't know how Joey would cope. He's never had a "real" pet, and he hasn't dealt with losing one, muchless a cat like Denali that he has such a deep connection with. Keep our kitty in your thoughts please. It's time to set up a vet appointment :(