Part of the difference between the dog foods available today and those of the previous generation is that scientists now understand that bodies need different nutrients at different ages and for different energy needs. A growing puppy or a dog nursing pups both have greater nutritional needs than a senior dog whose routine consists of getting up to go to the bathroom and napping. This is another way feeding your dog properly is made easier: Feed a puppy a puppy formula, an allergic dog a hypoallergenic formula, a working dog a protein-rich formula, and so on.

Puppy Food

Puppy foods are specially formulated to help develop strong bones and good muscle mass. If you read the ingredient panel, you'll see that puppy foods tend to offer more protein and vitamins than normal dog foods and are formulated for excellent health at this very important developmental stage.

When your dog is old enough, you should switch her to a food more appropriate for her next life stage. When this might be right for your dog is something you'll need to gauge. Talk to other owners of your breed, and especially with your dog's breeder. You want to gradually wean your puppy from a puppy food to a maintenance diet.

Maintenance Diet

This is the stage that includes the largest percentage of the dog population, as it's typically what's fed between the ages of ten to twelve months and six to eight years (before switching to a senior food). There are many formulations in this category, and each has its own claim to quality: there are highprotein formulas, natural formulas, lamb and rice, chicken and rice, beef, liver, and so on. The truth is, every dog is an individual, as is every dog owner. You need to prepare and feed something that works for both of you.

“Lite” Foods

Today, many foods for humans have been manufactured to reduce their overall calorie count, and the same is true for dogs. If you suddenly find that Rover looks like a barrel with four legs, you should consider switching to a lite formula dog food to help get her back into shape.

Lite foods are developed to deliver the same amount of vitamins, minerals, and proteins as other dog foods but with reduced calories. They tend to contain more fiber, which helps your dog feel full after a meal. Follow the directions and don't overindulge your dog with treats.

Even if your dog is not obese, you may find switching to a lite formula is better for him. Middle-aged dogs (from four to seven or eight years old) that don't exercise too frequently may be ideal candidates for a lite diet. After all, they don't need the protein and calories their more active friends do, but they still enjoy eating and want their regular, healthy meals.

Senior Formulas

When does your dog become a senior? That's a good question that's sometimes difficult to answer. It ranges from breed to breed and from dog to dog, though there is a general understanding that dogs aged seven or older are considered “seniors.” Some breeds, however, don't even reach that age, and are considered to be seniors before then. Your dog's breeder, your veterinarian, and other owners of your breed can help you determine when switching to a senior food would be right for your dog.

Aging means the loss of vigor and ability to perform feats once thought normal during the adult years. Seniors can't run or walk as fast. They sleep more. Their systems begin to deteriorate just as ours do. Senior dogs need a food that gives them as much energy as possible without making them heavier and slower. Many senior formulas contain the extra vitamins older dogs need, like glucosamine and chondroitin or extra vitamin C.

Hypoallergenic or Therapeutic Diets

If your dog's diet doesn't seem to be agreeing with her — her skin and coat are dry and itchy; she has loose stools; her energy level is off — work with your veterinarian to determine if she might be allergic to any of the ingredients in her dog food. Foods are being made with a variety of protein and carb sources now, including lamb, rice, fish, and sweet potato. A switch to one of these may dramatically clear up her condition.

A particular, recurring health concern may lead your veterinarian to prescribe a therapeutic diet for your dog. Several manufacturers now make these diets, which are prescribed by veterinarians to assist in the treatment of problems associated with particular organs or body systems and conditions.