Instructions
Determine your dog's breed. Sometimes this can be difficult to do with mixes or mutts, but try to determine what type of stock the dog comes from. Compare your dog to pictures online or in dog books for help when identifying breeds.
Research the breed. You should find general guidelines for normal adult weight for the dog. For example, average German Shepherds should have weights in the mid-70 pounds.
Examine your dog's ribs. It is helpful to know breed guidelines, but personal inspection is more accurate when determining ideal weight. Feel along its ribs. You should be able to feel each rib, but not be able to see more than two or three of them. If you can see them all, the dog is too thin; if you can't feel them, the dog needs to lose weight.
Examine and feel the dog's back where it meets his tail. A healthy dog should have a slight fatty padding here, but you should be able to feel the bone. If you cannot, it might mean that the dog is too heavy. If you can see the bone sticking out, the dog needs to gain weight.
Feel along the dog's spine and shoulders. Different dogs put on weight in different areas, so you should feel all of the listed areas to see whether the dog appears too thin or fat. Again, you should be able to feel the bone, but feel a slight layer of fatty padding between the skin and the bone itself.
Inspect the dog visually from the top and sides for signs that it might be overweight or underweight. When you look at the dog from the side, its stomach should be closer to its spine at the rear of the trunk than it is at the forward portion of the rib cage. If the angle from the ribs to the top of the back legs is too steep, the dog needs to gain weight. If the stomach does not tuck upward but instead slopes down, or is the same height as the ribcage, then the dog needs to lose a few pounds. From the top, you should see a waist on the dog in the area behind the ribs.
How to Find Your Dog's Ideal Weight
Dogs are like humans in one key regard when it comes to their health. If they are not at their ideal weight, their health as a whole will suffer. If a dog is underweight, it will be more prone to injury and can have low energy. An overweight dog is likely to injure itself in other ways. The extra strain excess weight puts on a dog's heart and other systems can cause it to have a much shorter life. Find the ideal weight for your dog and keep it there. This way, you help ensure it lives a long and happy life.