My vet is always pushing the food he sells as being better for my pet than the food I’m feeding. But, I think he’s just trying to make a buck selling me that over priced food!.
Not true.
First of all, veterinarians make very little on the food they sell- a few bucks a bag, is all- barely enough to pay the staff to inventory it and stack it. Food takes up a lot of
space, is an inventory nightmare and produces very little profit! So, there has to be something else motivating your vet to recommend specific food– your pet’s best nutritional health.
There is no one better than your vet to make dietary and nutritional recommendations for Your Pet. Your vet knows your pet better than anyone (except you!). The kid in the pet store making pet food recommendations doesn’t know anything about your pet’s health. They are educated by the pet food companies to emphasize whatever aspect of that food the company thinks will appeal to human purchasing sympathies. They are educated by the store management to “push” certain foods that are over-stocked in the store’s inventory. They are brainwashed by pet food companies to sell you food, regardless of the nutritional needs of Your pet.
Besides, why Ever, would you more readily believe the advice of a store employee, who has no formal education in animal nutrition, over the advice of your own 
veterianrian? A significant part of your veterinarian’s education was devoted to animal nutrition, how nutrients are tied to metabolic functions, right down to the cellular and molecular level, and the natural feeding habits of animals. Vets have all your pet’s nutritional needs in one place– their brain.
When a pet has special nutritional needs because of disease (liver failure, kidney disease, diabetes, etc) or nutritional deficits (Zinc-responsive dermatoses, hypothyroidism, etc) or obesity- the most common nutritional disease- your veterinarians recommendations are key to improving the health of your pet!
It’s true that presciption pet foods and veterinary lines of pet foods are more expensive than many over-the-counter foods. But, they are usually made by companies that 
put a lot of money into pet nutrition research and into the quality control of the manufacturing of their foods. There are far fewer food recalls from the Veterinary food companies than pet foods sold in the grocery store! Furthermore, your pet probably has a special need prompting your vet to make the diet recommendation. Your vet likely feels that your pet’s condition or over-all health can be improved by eating the special diet. That food is just as much as part of the treatment for your pet’s condition as any pill they could give you! And, if feeding the special diet improves your pet’s quality or length of life, reduces the number of pills you have to buy and the number of vet visits you have to make, isn’t the extra expense of the food worthwhile? A bag of prevention… is worth numerous trips tot he vet!
Try to remember that your vet is not trying to make money off you by recommending a diet change. Realize that they have sifted through all the gimmicks and fads for you, so the recommendations they make are not based on the latest pet food craze (like “vegetarian” and “grain-free”- when did berries become any more “natural” for dogs and cats?). Their recommendations are based on their thorough knowledge of animal nutrition and its intimate links with your pet’s particular wellness needs.