At constantly high level of Calcium in food the level of parathormone secretion falls and as a result osseous and cartilaginous tissues stop changing normally; bones become thicker and more dense. Those cartilages lingered in their development are subdued to unwarrantably high mechanic effects, caused by physical activity and, probably, excessive weight, that reduce cartilages durability. Impediment of changing in osseous tissue and loss of durability of cartilages may cause pain and serious disorders of supporting and motor systems - osteochondrosis, cutting osteochondritis, compression of spinal column, etc. These disorders are more probable and more serious in quickly growing breeds-the-giants. Excess of Calcium in food also impedes assimilation of other minerals and microelements such and Phosphorus, Magnesium, Copper and Zinc.
Thus, the excess of Calcium may cause a secondary lack of this element in organism.
The amount of Calcium consumed depends on food calorie content and Calcium content in consumed food. Since food ration is, first of all, based on energetic needs of puppy, the most logical thing to do is to determine the dependence between calcium content and energy value of food (instead of dry substance of the latter), which is evaluated as grams per 1000 kcal.
According to NRS 1985 the minimal need of calcium with respect to body weight is evaluated as 320 mg/kg at the beginning of growth process. Later this ratio reduces and for an adult dog it falls down to 119 mg/kg. The ration that at least includes 2.9 grams of calcium per 1000 kcal will cover the needs of growing puppy of any breed. For a food with a food value 3500-4000 kcal per 1 kg of dry substance the calcium content in dry substance is 1 percent, and, correspondingly, is 0.9 percent in dry food, which humidity is about 10 percent.
These figures were determined in 1995 by Association of American Feed Control Officials as an optimal recommendation for producers of dog foods. The Association is an official institution that controls the safety of foodstuffs. Relying on the latest researches in this area, the Association has established the maximum allowable value of calcium content in food: 7.1 g/1000 kcal or 2.5% of Calcium in dry substance, with food value between 3500 and 4000 kcal/kg of dry substance (AAFSO 1995).