Step 1: Realize there is a hole in the screen exactly the size of a dog's head.
Step 2: Close window.
Step 3: Count pets.
Step 4: Take down screen and frame. Pull out spline and the destroyed screen. Show it to dog. Marvel at his lack of remorse.
Step 5: Spline new "Pet Safe" screen into the frame and wonder if "Pet Safe" is a match for the dog-asaurus.
Step 6: Re-install freshly screened frame in window. Glare at all pets. Shake a finger at them. Marvel at their lack of interest.
Step 7: Realize there is a hole in a window screen exactly the size of a dog's head...