CFrance, good catch, I had to go back a carefully re-read the original post, and I had completely missed the missing door stop, O thought the doggie door was going outside. Sorry for the confusion.

I hope they aren't letting their cat outside.

A black racer is usually just jet black with no markings from what I've seen before.

Agree
 

I agree. Where I grew up in Texas we called them Puff Adders because of their Cobra-like posturing, and flattening of the neck when disturbed.

Given the circumstances, is it possibly a CATtlesnake?:1rotfl::1rotfl::1rotfl:

Good for you Jibuck. That's the way I read your post.
Residents who let their cats roam outside are asking for grief.

We had snakes in our other house get under the door stop and into the lanai and reinforced them. One still got through to our cats delight and our dismay. They love to show off and attempt to bolster the food pantry with such finds by bringing them inside. When we put heavy screening in the bottom panel of the cage, the opaque one, it helped but we found Koko could climb the screen to get a better look out and took out the screen panel with his weight. With his new knowledge of climbing the screens, he started chasing squirrels around the top and birds so big they could eat him. Finally, as others have posted, he only went out under close watchful eye. Our new cat has no such inclinations but has allergies, so we keep him inside safe and sound.