Porky Pets

The article that I found on National Geographic.com entitled Porky Pets caught my attention. My three year old golden retriever is 20 lbs. overweight and the vet suggests a special formula to help her lose weight. I think it is also necessary to mention that the dog food is about two times more expensive than any regular store brand.In the article it discuss how 1 in every four pets in America is obese which puts them at a high risk for diabetes, heart disease, and many other health problems. Which makes me want to provide the best for my dog, no matter how expensive. So my question to you is whether or not the diet dog food is worth it? And if the veteranarian(they only place you can buy the food) has created a monopoly like advantage?