Where do the animals dissected in schools come from?

We're dissecting cats in my anatomy class, and I was wondering if the cats were bred to be killed? The box the cat came out of said "Bio Corporation" which is the company that sells these. I called the company today is class and asked the women how the cats were treated. She replied with a rude "If you want to safe cats, then go to an animal shelter and adopt one." I was so appauld, considering that wasn't even the question that I asked. I just want to know the conditions that these animals are going through.