What It Does
Controls how much calcium and phosphorus your pet absorbs, directly determining bone and teeth strength. Unlike humans, dogs and cats cannot produce vitamin D from sunlight — studies show puppies develop rickets even with UV exposure if their diet lacks vitamin D. It must come entirely from food.
What You’ll Notice
Deficient pets develop soft, bendable bones, a stiff gait, reluctance to play, and are prone to fractures. Puppies may show bowed legs and stunted growth. Excess is toxic — causing vomiting and kidney damage.
Strong bones
Normal growth
Bowed legs
Fractures
Sources & Notes
Fatty fish, liver, egg yolks. All-meat diets without organ meats commonly cause deficiency. Never supplement without vet guidance — toxicity is dangerous.