Understanding canine sports today--how is the veterinarian involved (Proceedings)

The veterinarian's role in the health care of dogs is changing. We can no longer convince our clients to bring their dogs to us for regular health checks by having them come in for vaccinations. While we know that regular checkups are vitally important for dogs in preventing disease and early treatment of problems when they arise, pet owners are not quite as knowledgeable.

With sporting dogs preventative exams should be as much a part of their training as the actual practice of their sport. I usually recommend that young healthy dogs without previous injuries see a veterinarian every 6 months and during the examination, I will perform a full general physical exam, orthopedic exam and neurologic exam. If the dog has previously been injured but has made a recovery following treatment (whether surgical or rehabilitation), exams are to be performed every 3 months.

When we think of sports for dogs we usually think of racing and coursing or luring as with greyhounds; or of field trial dogs for hunting, or even sled dogs in the Iditarod. However, within the last 10 years or so, other sports have been gaining in popularity including agility, flyball, disk dogs (Frisbee catching), tracking for search and rescue, dock jumping and earthdogs. Over 800,000 entries in 2,147 American Kennel Club sponsored agility trials were recorded in 2008 alone. Flyball associations are now located in North America, the United Kingdom, Belgium, Australia, South Africa, Germany, Finland, and the Netherlands and in the US alone, over 8,000 entries were recorded by the North American Flyball Association.

With many of these increasingly popular sports, there is no specific breed requirements and because “anyone can play”, many pet owners enroll their dogs in these activities without prior knowledge of the sport on the part of the owner, and little to no training on the part of the dog. A major concern for veterinarians is that little to no research has been conducted to determine the effect of these sports on the dogs, what training is needed, and what is required to prevent injury or serious chronic disease in the participants.

In a survey of gundogs and retrievers in Great Britain, over 1300 dogs were surveyed and veterinary attention was sought for 47% of them. About 25% of dogs were injured during the hunting season and most of these injuries were considered minor but included foot injuries and lameness most commonly. Foot pad lacerations are common as well as nail trauma. Most of these injuries are treated by the owners themselves. Foot pad lacerations that are full thickness are recommended to have suturing performed. The suture should be large enough to withstand weight-bearing and the interrupted mattress suture is best to prevent tearing out of the sutures. Puncture wounds can be problematic in that the dog can develop deep digital flexor tendonitis, a career-ending problem.

Systemic antibiotics are recommended as well as surgical management with debridement and suturing of the puncture. Other common injuries in gundogs include lacerations and punctures to the thorax, abdomen, and head. These injuries require careful examination by the veterinarian for underlying body cavity penetration, foreign bodies, and infection. Many strains or sprains that result in lameness in gundogs are not attended to by veterinarians. Proximal thoracic limb injuries were treated by the owners commonly and many resolved in a few days. How many of these injuries result in chronic problems is unknown. Agility dogs also face injury to their proximal forelimbs more commonly than expected during competition.

Unlike gundogs, agility dogs have a level surface to work on but must jump far in long jumps and high as with hurdles (as do flyball dogs) and A-frames. In agility dogs the amount of impact to the forelimbs is tremendous, with approximately 45 N/kg body weight  (peak vertical force) sustained upon landing after a hurdle. These dogs always land with one forelimb first then the other, increasing the impact of one limb consistently in practice and competition, potentially predisposing these dogs to chronic overload injuries in the dominant limb. Flyball dogs always turn on the flyball box in the same direction-either right or left. This means that stress injuries are common to the carpus and tarsus. Thus, the veterinarian must assess these athletes for ligament and tendon laxity by using a goniometer to assess joint range of motion. It is also important to assess for long bone pain since stress fractures have been reported in gundogs.

A controversial mechanism of injury is through early spay neuter. Early sterilization can result in longer leg development in dogs and increases the risk of hip dysplasia and cranial cruciate ligament injury in dogs. In the study surveying injury to gundogs, very few ruptured their cranial cruciate ligaments but 91% were sexually intact.  In a recent retrospective study I have just completed, of 120 dogs with cruciate ligament rupture and 65 age and breed matched control dogs, we found that spay prior to 6 months of age results in an odds ratio of 4.3 over dogs that were spayed older than 6 months. I do not recommend spay neuter in sporting dogs before 5 months of age and some veterinarians do not recommend it until the dogs are 14 months of age.

Nutrition can play an important role in the development of injury in sporting dogs. Growing dogs must be restricted in calorie and calcium intake since excessive amounts of these in the diet can predispose some breeds to developmental orthopedic disease. Nutrition in racing greyhounds has been thoroughly researched and much research has been performed on the nutrition of sled dogs as well. Sled dogs may perform better on low carbohydrate diets with up to 61% fat, however, extreme diets are not recommended.

Most dogs will need 4,000 kcal ME/kg or more with 50-65% of the calories from fat and 30-35% of the calories from protein for high-energy sports. I recommend a supplement of fatty acids with omega 6 to omega 3 ratio of 5:1 to 10:1 to prevent or at least decrease the incidence of osteoarthritis. Total dietary fiber should be 3-7% of dry matter. Polycose is a glucose supplement given in water within 30 minutes following an event to replenish energy stores but do not use it if another event will be performed in less than 2 hours of administration. Dimethylglycine has no proven benefits, but carnitine as a diet supplement has been shown to increase the endurance of sled dogs.

In humans, creatine can increase their capacity for sustained intense exercise and arginine is supposed to increase performance as well but no controlled studies have been performed. Timing of feeding can be critical to not only the performance of sporting dogs but to prevent injury as well. Feeding is not recommended during periods of strenuous exercise nor immediately prior to such exercise. A light meal but plenty of water for hydration is recommended.12 Dehydration is vitally important to preventing injury in sporting dogs, especially under high ambient temperature conditions. Dogs that are not physically fit or weekend warriors especially are prone to dehydration and its damaging effects.

The sporting dog veterinarian must have a sound knowledge of the sport that the athlete participates in and they must be vigilant in their exam to identify chronic injuries as early as possible in order to prolong the athlete's competitive years.

References

Club AK. What is AKC agility? Agility Statistics: American Kennel Club, http://www.AKC.org, 2008.

Association NAF. Flyball Growth Trends: NAFA, http://www.flyball.org, 2008.

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Levy M, Hall C, Trentacosta N, et al. A preliminary retrospective survey of injuries occurring in dogs participating in canine agility. Vet Comp Orthop Traumatol 2009;22:321-324.

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Slauterbeck JR, Pankratz K, Xu KT, et al. Canine ovariohysterectomy and orchiectomy increases the prevalence of ACL injury. Clin Orthop Relat Res 2004:301-305.

Spain CV, Scarlett JM, Houpt KA. Long-term risks and benefits of early-age gonadectomy in dogs. J Am Vet Med Assoc 2004;224:380-387.

Dammrich K. Relationship between nutrition and bone growth in large and giant dogs. J Nutr 1991;121 S114-S121.

Kronfeld DS, Hammel EP, Ramberg CF, Jr., et al. Hematological and metabolic responses to training in racing sled dogs fed diets containing medium, low, or zero carbohydrate. Am J Clin Nutr 1977;30:419-430.

Marcellin-Little DJ, Levine D, Taylor R. Rehabilitation and conditioning of sporting dogs. Vet Clin North Am Small Anim Pract 2005;35:1427-1439, ix.