How much should you feed an overweight or obese dogs? Here are some general rules:
Chubby dogs: If your dog is a bit overweight, try increasing the daily exercise routine. Gradually increase exercise over 2 weeks unless limited by a medical condition. If these measures fail, cut out all treats and reduce daily intake of food by up to 25 percent.
Fat or obese dogs: Stop all treats except vegetables. Increase exercise gradually over 2 to 3 weeks if not limited by a medical condition. If these measures fail, reduce the total daily food amount by 25 to 40 percent, switch to a low fat/high fiber diet, and call your veterinarian to discuss your plans. Inquire about prescription-type reduction diets that can really be effective while providing balanced nutrition.
For more information, please read Nutrition in Dogs.