There are practical reasons to invest in the best clothing for extra large dogs, like keeping your canine warm and dry when temperatures drop, or making sure your pooch is visible and safe on walks. Then, there are items that may seem less practical for your extra large dog, like pajamas. However, you may find that your Mastiff or Dogo Argentino is less anxious at times when wearing cozy PJs. We like the Tony Hoby Female/Male Dog Jumpsuit Pajamas. They come in the most stylish stripes and prints, are made of breathable, soft cotton and are easy to get on and off thanks to snaps fasteners.