Dogs of all sorts get cold in the winter, from tiny chihuahuas to larger greyhounds. Even dogs with thick coats could use a good sweater if they are outside for prolonged periods of time in cold weather. There are many methods available for making canine apparel, some of which are easier than others. You can achieve professional-looking results and have the chance to embellish the finished product to suit your pooch's personality.
Measure your dog around the neck, just under the collar. Measure the girth of your dog's chest, behind his legs and around his back. Also measure his waist (the narrowest point of his body or where you would like the bottom of the sweater to end), and the circumference of his front legs. Measure from shoulder to shoulder, as well as the length from his collar to the beginning of his tail. Mark these measurements down with your paper and pencil.
Sketch out a pattern on a sheet of newspaper. While the finished sweater will look like a tube, your pattern should look like a tube cut in half and laid flat with holes cut out for the dog's legs. Cut the sweater larger than you think you will need, because you will need to sew the edges of the sweater to keep it from unraveling.
Use your pattern to cut the old sweater to the desired shape and size. Using the tapestry needle and thread, or sewing machine, hem any openings and sew the underside of the sweater shut. The sweater should now resemble a tube. Make sure to sew around the edges as well. If the fiber of the sweater is synthetic, you may wish to use a high-heat setting on the iron to melt them into place instead.
Try the completed sweater on your dog. If adjustments need to be made, do so. If you would like to add any embellishments, also do so.
Old sweaters can be bought very cheaply from thrift stores, and they are often deeply discounted in the summer months. The pattern may take some adjustments. You may want to use a sweater you don't particularly care for while making your first attempt.
Some dogs do not take to sweaters easily. If your dog is the sort who likes to chew on things, forgo embellishments, as they may pose a health hazard to the dog. Make sure all openings are wide enough or stretchy enough so that they do not cut off circulation to the dog's limbs.