1. Calcium is essential for developing strong bones and teeth, but growing bodies need a precise, balanced ratio of calcium to phosphorus, not just high calcium alone. 2. Over-supplementing calcium, especially in large and giant breed puppies, can actually cause developmental orthopaedic diseases, abnormal growth plate development, and skeletal deformities. 3. The growth phase in large breed puppies is a particularly sensitive window, their skeletal system is growing so fast that even small nutritional imbalances can have outsized effects. 4. Under-supplementation is just as much a concern, especially in smaller or toy breeds, or pets on home-cooked diets that aren't nutritionally balanced, where inadequate calcium can lead to weak bones and even fractures. 5. Home-cooked diets, however well-intentioned, frequently lack the correct calcium-phosphorus balance unless specifically formulated with veterinary guidance. 6. Bone and joint development in growing pets is a long game, what's fed in the first year often determines skeletal soundness for the rest of that pet's life.