It would appear to make sense that a dog such as a Great Dane or Saint Bernard, or even a Labrador retriever, needs a more calcium-dense diet as a puppy than a dog whose adult size will be smaller. After all, the logic goes, more calcium per calorie is needed to build the bones involved in the scaffolding of a large dog’s skeleton.
But ironically, the opposite is true. Large and giant-breed puppies, often defined as those who will grow to an adult size of 50 to 70 pounds or more, actually require less calcium-dense diets while they are still growing than dogs who will weigh less as adults. Why?
While adult dogs fed high-calcium diets can regulate the amount of calcium that they absorb from their food, puppies lack this ability, especially before 6 months of age. And because large and giant-breed puppies have steep growth curves during this time period, they are much more at risk than smaller puppies of absorbing too much calcium. Research has shown that this makes them more likely to end up with developmental bone diseases down the line. Their bones could grow too fast or become too thick, and those complications predispose a dog to complications including arthritis, hip and elbow dysplasia, and various other bone and joint problems that can have lifelong consequences.
Fortunately, dog food labels make it easy to tell if the food is right for your puppy that will grow into a large dog. If the label says the food is appropriate for “growth” (meaning for puppies) or for “all life stages” (which includes puppyhood), the Association of American Feed Control Officials (AAFCO) requires that the Statement of Nutritional Adequacy contain one of two phrases:
“including growth of large size dogs (70 lbs or more as an adult)”
“except for growth of large size dogs (70 lbs or more as an adult)”
Choosing the first one for your dog means the food will contain about 4.5 grams of calcium per 1,000 calories. The second one can contain food with as much as 6.25 grams of calcium for every 1,000 calories — about a 40 percent difference and enough to cause serious problems in susceptible breeds.
Note that while AAFCO chose 70 pounds as the cutoff, most veterinarians go with 50 pounds. That’s absolutely fine. There is minimal to no risk of feeding a lower-calcium diet to a puppy of any size. When in doubt, check with your vet.
How many months to feed the food
Puppies who will grow into small or medium-size adults mature fully by the time they are 12 months old. Some giant-breed puppies, on the other hand, do not reach physical maturity until they are closer to a year and a half. All puppies should be fed food appropriate for growth until they reach 12 months of age, or skeletal maturity if 12 months isn’t enough.