Thursday, July 28, 2011

Canine Performance Nutrition: An Overview

This is a paper I wrote for a nutrition elective rotation I took in March 2011.  I am posting it as I believe many might find it interesting.  I'll be posting more on nutrition in the future.  Enjoy!
While the majority of dogs in developed nations enjoy fairly sedentary lives, more and more owners are including their canine companions in a variety of activities and sports.  Dogs now commonly join their owners to compete in the newer sports of agility, flyball, and dock diving.  Performance events such as herding, protection, hunting, and sledding remain popular and blur the lines between work and play for dogs and their handlers.  In addition, dogs provide a valuable service to military, law enforcement, and the community through patrol work, scent detection, and search and rescue efforts.  While nutrition is not a substitute for the correct genetics, training, and conditioning of performance dogs, many owners are very interested in the nutritional needs of their canine athlete.  To reach peak performance through optimal nutrition, owners and veterinarians should calculate the caloric needs, consider a diet that complements the performance expected based on the components of the food, and develop a feeding plan that optimizes peak performance.

Most nutritional studies of canine athletes have traditionally focused on the sports of dog racing and dog sledding.  The two average participants in these activities are greyhounds and husky-type dogs respectively.   Greyhound racing is a highly anaerobic sport that short in duration which is reflected in the type IIa fast twitch muscle fibers that dominate a greyhound’s lean muscle mass (Hill 1998), while some dog sled races such as the Iditarod are over one thousand of miles in length covered over the course of up to two weeks.  Most other canine activities fall somewhere in between these two extremes, with sports like agility and flyball being more similar to sprint racing and hunting field trials and ranch livestock work of several days duration being more similar to sledding (Toll et al. 2010).  Understanding the nature of the activity that the canine athlete is participating in is crucial for making nutritional recommendations to the owner.

In deciding a nutrition plan for a canine athlete, it is helpful to understand some of the differences in how food is utilized by the body depending on the type of exercise.  Parallels between the nutritional needs of human and canine sprinters versus marathon runners are commonly made in comparative studies of exercise physiology, though the dog in general is better suited to oxidative metabolism of fats and dogs metabolize free fatty acids at twice the rate as humans (Hill 1998).  However, most sources suggest that as in humans, sprinters such as greyhounds do best with higher levels of carbohydrates to mobilize glucose during short durations of exertion; in contrast, endurance runners such as sled dogs or hunting dogs may exhaust their stores of glycogen and may have improved performance on high protein, high fat, and low carbohydrate foods (Hill 1998).  Different studies have also shown hematological effects such as “training-induced anemia” (Hill 1998) and decrease in total protein in serum (Hinchcliff 2000) before and after strenuous prolonged exercise in sled dogs that may be exacerbated if the protein levels are not moderately high, though one smaller non-cross over study showed a vegetarian- based food did not significantly alter either blood values or performance of short distance sprint racing huskies (Brown 2009).  

In addition to the basic components of the food, meeting but not exceeding the energy requirements of canine athletes can be challenging both in the trial season and in the off season.  As most greyhounds run only a short distance at a high intensity level every few days, most sources suggest that their caloric requirements are likely similar to other moderately active dogs with a life stage factor of 1.6.  On the other extreme, long distance sled dogs may require a life stage factor of over 10 not only due to physical exertion, but because of extremely cold environmental conditions (Hand et al. 2010).  A highly calorically dense diet is required to meet the needs of the long distance sled dog.  Owners and kennel workers should be aware that feeding to these levels in the off season is not advised and that they may return the dog to a lower plane of nutrition after the training and trial season is over or risk gaining an undesirable amount of weight.  Dogs that compete in other short but explosive sports such as flyball and agility are likely closer to greyhounds in their need for caloric intake and will likely not need a large increase in their rations during competition season.  Herding, police, and hunting dogs would likely be in between the extremes of caloric requirements.

Some special considerations of certain canine athletes (racing dogs, sled dogs, and hunting dogs) may include oxidative stress both from the physical exertion itself and the addition of extra animal or plant based fat sources for energy (Pasquini et al. 2010, Hinchcliff et al. 2000).  Supplementation of 400 IU of vitamin E beyond what is in typical commercially available diets have been suggested by some authors to account for the loss of antioxidants from the stress of heavy exercise and oxidation of high levels of dietary fats for sled dogs (Reinhart et al.).   In addition, dogs that rely heavily on their olfactory sense, such as detection or search and rescue dogs, may benefit from fatty acids in their diets.  Not only are certain PUFAs  anti-inflammatory, but scent detection relies on the olfactory epithelium, of which fatty acids are integrated as components of the cell membrane (Toll 2010).  As a general rule, many “weekend warrior” types of canine athletes that accompany their owners to the hiking trails or to an agility trial may not need special dietary supplements as long as their nutritional requirements are being met by feeding a high quality commercially prepared diet.  Other canine athletes such as hunting dogs or sled dogs may be fairly sedentary during all but the competition seasons when they are asked to perform strenuous and prolonged exercise at high levels.  Diet changes both at the onset and peak times of training should be gradual if possible.  It should be communicated to owners that while nutrition is vital, training, conditioning, and genetics will be of greater value for performance than supplements or special diets. 

Works Cited
Brown WY, Vanselow BA, Redman AJ, et al.  An experimental meat-free diet maintained haematological characteristics in sprint-racing sled dogs.  Br J Nutr 2009; 102:1318-23.
Hinchcliff KW, Reinhart GA, DiSilvestro R, et al.  Oxidant stress in sled dogs subjected to repetitive endurance exercise.  Am J Vet Res 2000; 61:512-17.
Hill RC. The nutritional requirements of exercising dogs.   J Nutr 1998; 128:2686S–2690S.
Pasquini A, Luchetti E, Cardini G.  Evaluation of oxidative stress in hunting dogs during exercise.  Res Vet  Sci 2010; 89:120-23.
Reinhart G, Hinchcliff K, Reynolds A, et al.  Supplementing vitamin E to sled dogs.  Iditarod website. Available at:  Accessed March 24, 2011.
Toll PW, Gillette RL, Hand MS.  Feeding working and sporting dogs.  In:  Hand MS, Hatcher CD, Remillard RL, Roudebush P, Novotny BJ, eds.  Small animal clinical nutrition.  5th ed.  Topeka:  Mark Morris Inst, 2010; 321-352.