I have a cat that needs to be pit down. We've had him for 10 years. About a week ago he started hissing and growling at me..in an attack mode. He's in indoor cat. My wife is a diabetic and we can't risk him attacking her. How should I handle this?

It's obvious something has caused the cat to feel insecure and unsafe. Why is you're first thought to put the cat to sleep. This is completely selfish and absurd. If you care about this cat talk to an cat behaviorist. Hissing is not a reason to put an animal down. It sounds to me like your simply looking for an excuse to get rid of the cat that doest trust you. Find a home for it if you don't want it. I feel sorry for this cat and your wife. And being diabetic has nothing to do with anything.

I would go with Judith answer, the ark is pretty good with having an answer for you

Call Ark and explain to them what is going on. Maybe he is sick.