DELAYED CASTRATION OR OVARIOHYSTERECTOMY

A controversial mechanism of injury in sporting dogs is through early spay or neuter because of loss of sex hormones during growth and development. Early sterilization can result in longer leg development in dogs and an increased risk of hip dysplasia and cranial cruciate ligament injury.^29-31 Delaying gonadectomy in larger breed dogs may reduce the incidence of some orthopedic diseases including hip osteoarthritis, cruciate ligament disease, and other problems related to delayed growth plate closure in sex hormone-deficient puppies.^29,30,32 Because of these risks, I do not recommend gonadectomy before 6 months of age in sporting dogs. In all large- and giant-breed dogs, I recommend waiting to perform surgery until they are 10 to 12 months of age.

NUTRITION

Diet content

Excess caloric and calcium intake must be avoided in growing dogs since it can predispose some breeds to developmental orthopedic disease.³³ Total dietary fiber should be 3% to 7% of dry matter.³⁴ Sled dogs may perform better when receiving low-carbohydrate diets with up to 61% of the calories from fat, but a diet without any carbohydrates is not recommended.³⁵ Most dogs will need 4,000 kcal metabolizable energy/kg or more, with 50% to 65% of the calories from fat and 30% to 35% of the calories from protein for high-energy sports.

Supplements

I recommend a supplement of omega-3 fatty acids such as fish oil to decrease the clinical signs of osteoarthritis and to reduce matrix metalloproteinase production in joints, which, when increased, increases the signs of osteoarthritis by degrading proteoglycans and cartilage.^36,37 Supplementation with omega-3 fatty acids also results in decreased production of prostaglandin E₂, a mediator of pain and inflammation in osteoarthritis.³⁶ Theoretically, a diet rich in omega-3 fatty acids would slow the development of osteoarthritis in athletes by reducing cartilage degradation, allowing them to compete at peak performance for longer periods.³⁸

Polycose (Abbott Nutrition) is a human glucose supplement that can be given to dogs in water (1.5 g/kg in 1 pint of water) within 30 minutes after an event to replenish energy stores. It should not be used if another event will be performed in less than two hours of administration since there will not be enough time to absorb the glucose source and gastrointestinal upset may result.

Dimethylglycine has not been proven to improve performance in racing greyhounds, but carnitine as a diet supplement (22 to 50 mg/kg once daily³⁹) has been shown to increase endurance in sled dogs.^40,41 L-carnitine at a dosage of 100 mg/kg once a day may increase muscle force and delay muscle fatigue in dogs, which could reduce injury to bone and joints due to muscle fatigue.^42,43 In people, creatine can increase the capacity for sustained intense exercise, and arginine is thought to increase performance as well, but no controlled studies have been performed.³⁴

Timing

The timing of feeding can be critical to not only the performance of sporting dogs but to the prevention of injury as well. Discomfort from a large volume of food in the dog's stomach could result in not only reduced performance, but, theoretically, poor balance, resulting in a stumble or fall that causes injury. Feeding is not recommended during periods of strenuous exercise nor immediately before such exercise because gastric emptying is delayed during exercise.⁴⁴ A large volume of food in a dog's stomach could cause discomfort and affect performance and could increase the risk of gastric dilatation-volvulus if breeds predisposed to gastric dilatation-volvulus are exercised within two hours after feeding.⁴⁵ Mild restriction of food intake in racing greyhounds improves their running speed over dogs fed ad libitum.⁴⁶ A light meal but plenty of water for hydration is recommended.⁴

Water intake

Hydration is important to prevent injury, especially in high ambient temperatures, because dehydration results in severe muscle fatigue that can result in joint and musculoskeletal injury.⁴⁷ Dogs that are not physically fit or that are weekend warriors may be prone to dehydration and its damaging effects since they have reduced muscle tone and strength.^48,49 Be sure to remind owners and trainers of the importance of having water available at all times, even during competition, to reduce the incidence of dehydration.⁵⁰