Measure your pet using a tape measure to know how big the pet door should be. Measure the length of the pet from legs to head and the width from shoulder to shoulder.
Measure the dimensions of the sliding glass door to know the needed height of the pet door.
Purchase a pet door panel for sliding glass doors that fits the dimension of the pet and the door. For the easiest installment option, purchase a door that requires no additional tools for attaching the door. This door is also the best for short-term installation, such as if you plan to move or are going to replace the sliding door soon.
Insert the bottom of the pet door panel into the floor track of the sliding door.
Push the spring down on the top of the frame panel to fit the frame into the top track. If the pet door panel comes with tightening knobs, tighten them so that the panel stays in place.
Make any fine adjustments if needed to position the panel so that it fits in place on the sliding door.
Close and lock the patio door at all times to keep the pet door panel locked in place.