To determine whether your dog is overweight, stand over him and check for a waist— there should be a visible indentation behind his ribs.
Obesity is the most common canine nutritional disease in this country, occurring in up to 25% of dogs. While the many problems associated with weight gain are frightening, it's reassuring to know that by keeping your dog at a reasonable weight, you can reduce his chances of diabetes, heart disease, orthopaedic problems, and possibly even cancer.
To determine whether your dog is overweight, stand over him and check for a waist— there should be a visible indentation behind his ribs. All dogs, regardless of breed should have a waist. Then give him a hands-on test. Can you feel his ribs? They shouldn't be sticking out, but you should be able to find them through a layer of skin and muscle, and be able to easily count them. If all you feel is rolls of fat, it's time to begin a diet and exercise plan.
If you feed your dog a prepared pet food, the label on the package will provide a guideline as to how much to feed daily. These recommendations are a guideline only and you should make adjustments according to your dog's individual needs. Don't forget to take into account the calories in treats and other titbits he eats—they shouldn't make up more than 10% of his daily calorie intake.
Try to exercise your dog as much as he is able. The more muscle he maintains, the more calories he'll burn and less fat he'll carry. Not only that, but when you fill his time with fun activities, he'll spend less time hanging around the food bowl. This increased activity won't just benefit your dog, it will benefit you.
Finally, be sure to take your dog to your veterinarian for a check-up and expert advice. Your vet may give you guidelines on exercise appropriate for your dog's age and health as well as specific advice on how much he should be eating. He can also check for, and treat, any weight-related problems.