Write an article based on this summary:

Make one long horizontal line across the bottom of the bag. Call your dog over and command him to stay. Hold the plastic bag against your dog’s body. Cut the marked lines on the plastic bag. Place the poncho on your dog.
This cut line will open the bag up on the long side so you can drape the bag over your dog’s body. The long strip of plastic will then act as the belt to keep the poncho attached to your dog. Using a cut line across the bag, starting from the closed end to the open end, will reduce the time it will take to get your dog's legs into the poncho. Rather than have to make four holes in the bag for his four legs, you can simply place the poncho over your dog so his body and legs are covered by the bag. To make sure the poncho fits your dog properly, you will need to get your dog to stay in one spot and remain still as you measure the bag against his body. If your dog doesn’t like to remain in one spot for an extended period of time, you can use small treats to encourage him to stay still for at least three to five minutes. This will help you measure the dimensions of the poncho so it fits your dog properly. Hold the marker in the other hand as you note where you are going to cut the plastic bag.  Using your dog as a marker, draw a half circle shape on the top corner of the bag, along the closed part of the bag, so your dog’s neck and head can fit through the poncho. Make sure the circle is big enough to fit your dog’s head and neck comfortably. You will then need to draw a longer half circle on the back end of the bag so there is enough room for your dog’s bum and tail. Use your dog’s body as a marker to ensure the longer half circle is big enough for your dog. Once you have your cut lines, place the plastic bag on the ground or on a table and cut along the marked lines. Once you have cut the poncho to fit your dog’s measurements, place it on your dog so your dog’s body is covered by the poncho. It should drape over him like a sheet. His tail, neck, and head should all remain outside of the poncho and go through the half circles you made on the bag.  Take the long strip of plastic and wrap it around your dog’s belly, securing the poncho to your dog. Tie the strip several times so the strip is snug and not too tight around your dog. Let your dog walk around to make sure the poncho is comfortable for him and easy to move in. You can then put on your own poncho and head out for a walk.