RELATIONSHIP OF NUTRITION TODEVELOPMENTAL SKELETAL DISEASE IN YOUNG DOGS
By: Daniel C. Richardson & Phillip W. Toll
Developmental skeletal disease is common in large and giant-breed puppies. One manifestation, hip dysplasia, affects millions of dogs. Genetics, environment, and nutrition all contribute to developmental skeletal disease. Of the nutritional components, rate of growth, specific nutrients, food amounts consumed, and feeding methods influence skeletal disease. Excess energy and calcium are known risk factors; therefore, the level of these nutrients in the food should be near the Association of American Feed Control Officials minimum requirement. Puppies should be fed a growth-type food using a food-limiting technique. All puppies should be weighed and evaluated at least every two weeks. Amounts fed should be increased or decreased based on weight and body condition score.
The musculoskeletal system changes constantly throughout life. These changes are most rapid during the first few months of life and slow with skeletal maturity (about 12 months for most breeds). The skeletal system is most susceptible to physical and metabolic insult during the first 12 months of life because of the heightened metabolic activity. The physical manifestation of these results can be lameness and/or altered growth. Both can affect locomotion and/or soundness of adult dogs.
Developmental skeletal disease is a multifactorial process that has genetic, environmental, and nutritional components. These skeletal abnormalities primarily affect fast growing, large-breed dogs. Lack of careful genetic monitoring can introduce and propagate disorders (e.g., hip dysplasia, osteochondrosis) that are difficult to eliminate. Trauma, whether obvious (e.g., hit by a car) or subtle (e.g., excessive weight) can adversely affect relatively weak growth centers and cause skeletal disease (e.g., angular limb deformities). Nutrient excesses (e.g., excess calcium supplementation) often exacerbate musculoskeletal disorders.1-4 This article reviews the role of nutrition in developmental skeletal disease in young dogs.
Nutrition and Skeletal Disease
The role of nutrition in developmental skeletal disease is complex. Rate of growth, specific nutrients, food consumption, and feeding methods have all been shown to influence skeletal disease. Large and giant breeds are most susceptible to developmental skeletal disease, presumably because of their accelerated growth rate.4,5 Dietary deficiencies are rare in young, growing dogs fed commercial growth foods.6 Problems associated with dietary excess are far more likely, especially if a high quality growth food is supplemented with minerals, vitamins, and energy.6 The following review discusses some of the more critical nutrients in developmental skeletal disease.
The energy needed for any individual depends on breed, age, neuter status, and activity levels. In general, growing puppies require twice as much dietary energy as adults for body maintenance, activity, and growth. The need is greatest right after birth and decreases as the dog grows and matures. Rapid growth in large and giant-breed dogs increases the risk of skeletal disease.4,5 Excessive dietary energy may support a growth rate that is too fast for proper skeletal development and results in a higher frequency of skeletal abnormalities in large and giant-breed dogs.7 Because fat has twice the caloric density of protein or carbohydrate, dietary fat is the primary contributor to excess energy intake.
Excess energy leads to rapid growth. Dietary energy in excess of a puppy's needs will be stored as body fat. Body condition scoring evaluates body fat stores and therefore correctness of energy intake. Maintaining appropriate body condition during growth not only avoids excess body fat storage, but also helps control excess growth rate. Limiting intake to maintain a lean body condition will not impede a dog's ultimate genetic potential. It will only reduce food intake, fecal production, obesity, and lessen the risk of skeletal disease.8 Energy or food-dose calculations can only be used as general guidelines or starting points that must be modified based on frequent clinical evaluation of each puppy because individual needs can vary widely. (Fig. 1). Physical evaluation or body condition scoring should be done at least every two weeks (See Evaluation of Feeding Methods and Scoring to follow).
Unlike other species, protein excess has not been demonstrated to negatively affect calcium metabolism or skeletal development in dogs. Protein deficiency, however, has more impact on the developing skeleton. In Great Dane puppies, a protein level of 14.6% (dry matter basis) with 13% of the dietary energy derived from protein can result in significant decreases in bodyweight and plasma albumin and urea concentrations.9,10 The minimum adequate level of dietary protein depends on digestibility, amino acids, and their availability from protein sources. A growth food should contain > 22% protein (dry matter basis) of high biologic value .11 The dietary protein requirements of normal dogs decrease with age.
Feeding treats containing calcium and/or providing calcium supplements further increases daily calcium intake. Two level teaspoons of a typical calcium supplement (calcium carbonate) added to the growth food of the 15-week-old, 15-kg Rottweiler puppy would more than double its daily calcium intake. This calcium intake is well beyond the levels shown to increase the risk for developmental bone disease. A recent review article best sums up the need for calcium supplements: "Because virtually all dog foods contain more calcium than is needed to meet the requirement, the use of a calcium supplement certainly is unnecessary. Now that the deleterious effects of excess dietary calcium have been delineated, we can say that the feeding of calcium supplements not only is unnecessary, but, in fact, contraindicated!"