A Heart Stopping Moment

This morning I was in my bedroom reading and answering emails when I heard a dog squealing! Like when a dog is being beaten kinda squealing.
I ignored it the first time since I've never heard our girls do that and we have a couple of dogs in the complex, one of which is a labrador pup.
When it happened again a few seconds later I got up and looked out the window. I couldn't see anything but I did see Thelma standing near my front door looking at the pool.
And then it happened again!
I ran downstairs thinking that perhaps the pup had gotten into our yard and fallen in the pool, or was being chased by Thelma and Louise since they don't like it when the pup comes near our gate.
I got our the front door and found Louise IN THE POOL!!
She was the one squealing!!
They have both been shown where the pool steps are- we put them in the pool last summer so they could orientate themselves, just in case- and she was at the first step (the deeper one) but hadn't moved over far enough to find the second, higher step and she couldn't get out!
My heart nearly stopped!
I pushed her gently to the second step and helped her out of the pool as she's too heavy for me to lift, especially soaked to the skin!
I then sat her on one of their outside rugs in the sun and rubbed her hard with a towel to try and help her get dry quickly. It is a rather chilly day today even though the sun is shining.
She seems no worse off for the incident, but I'll be keeping an eye on her to make sure she hasn't caught a cold or something.
I would love to know how she fell in the pool!