Too little calcium along with low levels of vitamin D may result in rickets, soft bones that bend out of shape under the weight of a pet. Supplementing diets of large breed puppies with excessive amounts of calcium can cause the development of bones that are large but low in bone density and strength. Fortunately, bone abnormalities are highly unlikely when a pet is fed a nutritionally complete and balanced pet food and there is no excessive calcium supplementation. As important as dietary calcium is, it does not work alone. Many mineral nutrients are interdependent and cannot function as a single element.
Calcium is interrelated with phosphorus.
A proper ratio of the two minerals is needed to ensure their utilization by a pet. Animal nutrition studies show that calcium and phosphorus should be included in a pet's diet at a ratio of 1.0 to 2.0 parts calcium to each 1.0 part phosphorus. Widening ratios beyond this point may be detrimental to bone calcification. If the amount of phosphorus far exceeds the amount of dietary calcium, bone abnormalities may occur. Meats are deficient in calcium and the ratio of calcium to phosphorus is very poorly balanced.