Immaturity, pregnancy, environmental changes, digestive upsets, sickness, injury or performance racing are common stages that may result in your pet becoming deficient in key nutritional elements. Dogs that eat only a raw meat diet or pregnant or lactating dogs may require additional calcium supplements to remain in optimal health. Sick or injured animals that may be too weak to eat a normal diet require supplements such as Nutrigel or Lectade to restore their strength and bodily functions.