Two factors that can affect performance are weight and nutrition. Every dog should be at a healthy weight, but the canine athlete should be lean and muscular. You can feel all his ribs, and he doesn't carry any extra fat. Gently pinch the skin on his back. You should be able to gather only a small amount with your fingers. A normal weight for the golden retriever that spends her days playing with the kids is probably way too heavy for the golden that competes in field trials. Additional weight, even if it doesn't seem like a lot, can contribute to injuries. Carrying too much weight causes or predisposes a dog to ruptured anterior cruciate ligaments, arthritis, and intervertebral disc disease, to name only a few.

Nutrition

Athletic dogs need special diets. With all the energy they expend, a nutrient-dense diet is a must. But beyond that, the type of food your athletic dog needs depends on his sport. Sprinters, such as agility or weight-pull dogs, need a diet high in carbohydrates. Nutritional needs vary for dogs involved in intermediate-level activities, which may last a few minutes to a few hours. A rule of paw is that the more work they do, the more dietary fat they need. And dogs that do endurance sports in extreme temperatures, such as sled dogs, need a diet very high in fat. It's also important to factor in whether your dog competes year-round or only seasonally. Off-season, a normal diet will serve him best to prevent weight gain.

Performance Diets

A number of diets are available to enhance a dog's athletic performance. Called performance diets, they usually contain about 20 percent fat, which provides more energy than carbohydrates and protein. At least one study has shown that athletic dogs fed a performance diet were better able to maintain their body weight and condition than dogs on a lower-fat maintenance diet, and they performed better. That said, high levels of protein are important, too. When athletic dogs get their energy from fat, their bodies can use protein for tissue repair and other functions, reducing the incidence of injuries. Remember that performance diets are suited only to dogs in competition. Your Labrador retriever may have a huge amount of energy but if all he does is play fetch with your kids and go jogging with you occasionally he doesn't need a performance diet.