If your dog has congestive heart failure, their veterinarian may have recommended changes to their diet. Other chronic conditions may also be present which can affect your dog's diet. It's important to adhere to the new changes in your dog's diet as much as possible because this has a positive effect on their health.
Dogs that have congestive heart failure tend to retain chloride, sodium and water. This is why it's important to limit the intake of sodium and chloride through your dog's food.
It may be difficult to do this with a regular food that's designed for adult dogs. However, since approximately 1/3 of dogs over the age of 10 have heart problems it's relatively easy to find special diets that are formulated with less sodium chloride (salt).