Introduction
No, it is not puppy fat, your dog is six years old! No, it is not its thick winter coat, it is fat! No, your dog is not just ‘well fed’, it is seriously overweight, i.e. obese, 
and will have a shorter life expectancy than other dogs that do have a normal weight. Veterinarians countrywide have to fight with similar arguments by dog owners, that don’t want to recognize that their dog is overweight.
Obesity in dogs can lead to, and aggravate, a variety of illnesses of joints, bones, heart and the metabolism. Obese dogs are more likely to suffer from diabetes and arthritis amongst others. And they do have a significantly shorter life expectancy, several years shorter to be exact.
Diagnosis
Normally the diagnosis will be pronounced by the vet during a routine or vaccination visit. While most cases of obesity in dogs are caused by an imbalance of calories eaten (too many) and calories spent (too less exercise), in rare cases a sudden increase in weight can be the symptom of a more serious, underlying, illness. But as long as this is excluded by the vet, there is really no excuse for having a dog that is too fat.
Symptoms or How do you know that your dog is too fat
When you look down on your dog, you should actually see a waistline, extremely hairy dogs like Chow-Chows are excluded from this test 
And if you dig your fingers in the coat on the sides of the chest, and through the under coat, you should be able to feel the ribs. Each breed has also a normal weight range, which can, to a certain extent, be used to see what kind of weight is normal for which breed. Take for example the Chihuahua. The breed standard says that a typical Chihuahua should not weight more than 6 pounds / 3 kilograms. If yours is of average size, but weighs more, chances are very good that it will be too fat. But when in doubt, always ask your vet first, he can tell you exactly how much weight your dog needs to shed.
Treatment
Feed less, but higher quality food and exercise more, just as for humans. Your vet will be happy to advise you on the best solution for you and your dog. As a rule of thumb, the higher the quality of the dog food is, the less the dog needs. That can set off some, or all, of the costs that come with buying a more expensive product. I personally would recommend going for one of the major brands of organic, natural and holistic dog foods, as these provide not only the best value for money, but have also less fillers, additives, antibiotics and other unwanted ingredients that many harm your dog in the long run. As part of the treatment plan your vet will give you, here some additional tips:
- Switch from free feeding to a feeding schedule to regain control about how much your dog actually eats.
- Decrease the food amount slowly, but steadily, that helps the dog to adjust better and avoids, hopefully, excessive begging.
- Reduce treats and, or, switch to treats that have less calories, such as carrot sticks.
- Stop feeding table scraps and human food to your dog. A small piece of pizza is for a toy poodle, what is, in comparison, half a pizza for you. Just do the math, 20g of human food consumed by a 10 pound dog equals 320g of food for a person that weights 80 kilos. Plus the salt, spices and grains contained in my human foods are unhealthy for dogs in any amount, no matter how tiny.
- Stop counter surfing (aka stealing) and garbage eating on walks with appropriate training. If your dog is one of those, that devours every piece of food it finds on walks, a muzzle might be helpful.
- Use a smaller bowl, your dog will not care, but you will feel better as the dog bowl still looks full
- Increase exercising slowly, especially if your dog is severely obese. Sudden, harsh exercise can kill, or at least harm, a dog that is already struggling to jump on the couch. So, please be careful and follow your vets’ advice. And, btw, swimming is a great, low impact and aerobic exercise that helps to slim down while protecting the joints from too much impact.
How to Weigh a Dog
During a canine weight loss regime, you should weigh your dog weekly. With smaller dogs this is easy. Just weigh yourself alone, then take your dog in your arms and weigh the both of you. Subtract the first amount (you alone) from the second amount (you and dog) and you get your dogs weight as a result. With bigger and huge dogs this might not be practical, unless you are a professional weight lifter that can hoist up a Great Dane in his arms and has a sidekick to read the scale;-) In this case you have to rely on the scale in your vets’ practice or, if you live in the country site, use a publicly accessible cattle scale.
Prognosis
The prognosis depends solely on you the dog owner, in the end it is you that opens the cupboard, takes out the dog food and fills the bowl. If you are consistent and strict, both with the canine weight loss regime and exercise plan, your dog will lose weight.
Costs
There are no special costs, other than regular vet visits, involved. Quite the opposite actually, you will save money as your dog will be healthier (less vet costs in the long run) and you will spend less money on food. You will even be able to feed your dog a higher quality food, as you need less of it to achieve the same health effect.
Summary
If you want your dog to live a long, healthy and happy life, treating dog obesity is an absolute must. If you neglect this part of dog care chances are that you end up with a dangerously overweight dog that suffers from multiple health issues and dies many years too soon.